tag:blogger.com,1999:blog-78351300992836846492024-03-18T16:47:10.163+07:00belajar AstronomyUnknownnoreply@blogger.comBlogger205125tag:blogger.com,1999:blog-7835130099283684649.post-10551771346467422872020-03-01T19:20:00.001+07:002020-03-01T19:27:04.167+07:00Free Astronomy textbook<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibj1GItFXPd2Oioo71lkdhIn0jTLixF-ar1fbM61kd6K0JHi82rIKRdvHW9PRXGjfZKgSUihA3kI555jZFvzk1QFeMHsKLvcLB417TeYm86870Yn76293iiCIXRRpedCYW1vzodo9AhEUh/s1600/Screen+Shot+2020-03-01+at+19.21.59.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="960" data-original-width="744" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibj1GItFXPd2Oioo71lkdhIn0jTLixF-ar1fbM61kd6K0JHi82rIKRdvHW9PRXGjfZKgSUihA3kI555jZFvzk1QFeMHsKLvcLB417TeYm86870Yn76293iiCIXRRpedCYW1vzodo9AhEUh/s320/Screen+Shot+2020-03-01+at+19.21.59.png" width="248" /></a></div>
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<span class="s1" style="font-kerning: none;"><i>Astronomy</i> is designed to meet the scope and sequence requirements of one- or two-semester introductory astronomy courses. The book begins with relevant scientific fundamentals and progresses through an exploration of the solar system, stars, galaxies, and cosmology.</span><br />
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<span class="s1" style="font-kerning: none;">The <i>Astronomy</i> textbook builds student understanding through the use of relevant analogies, clear and non-technical explanations, and rich illustrations. Mathematics is included in a flexible manner to meet the needs of individual instructors.</span><br />
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<b><span style="color: #0b5394;">Download for free at <a href="https://openstax.org/details/books/astronomy">https://openstax.org/details/books/astronomy</a></span></b></div>
Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-7835130099283684649.post-33685646789968594672019-08-28T11:17:00.001+07:002019-08-28T11:17:26.666+07:00Problems of International Astronomy Olympiad (2011)Problems: <a href="http://www.issp.ac.ru/iao/">http://www.issp.ac.ru/iao/</a>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-34287427277385528152019-08-28T11:06:00.004+07:002019-08-28T11:17:33.991+07:00Problems of International Astronomy Olympiad (2015)Main webpage: <a href="http://www.issp.ac.ru/iao/2015/iao15_e.html">http://www.issp.ac.ru/iao/2015/iao15_e.html</a><br />
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Problems link: <a href="http://www.issp.ac.ru/iao/2015/booklet/index_e.html">http://www.issp.ac.ru/iao/2015/booklet/index_e.html</a><br />
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<br />Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-56859431558668967622011-03-20T00:27:00.008+07:002011-03-20T00:59:21.648+07:00Supermoon 19 Maret 2011<div style="text-align: justify;">Karena fenomena Supermoon ini cukup heboh dan banyak menimbulkan salah persepsi, mari coba dibahas sedikit meskipun sebenarnya fenomena ini bukanlah fenomena astronomi yang penting. Impact atau efeknya hampir tidak ada selain tinggi air pasang air laut sedikit lebih tinggi.<br /><br /></div><div style="text-align: justify;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIf8EN2XLytdkWYA4Yn4T7kDCdq0FbEOVz58nEXbLQX9PpND0xOI1vstCA2E8uaZXAsZay8THKMd4mVWHM4FT_l0TY4kFVQRy2pduxr3KvPdjjg7ywgq89QgncoSjX_T7LWmFpzC3aAa5X/s1600/image_mini.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 198px; height: 200px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIf8EN2XLytdkWYA4Yn4T7kDCdq0FbEOVz58nEXbLQX9PpND0xOI1vstCA2E8uaZXAsZay8THKMd4mVWHM4FT_l0TY4kFVQRy2pduxr3KvPdjjg7ywgq89QgncoSjX_T7LWmFpzC3aAa5X/s400/image_mini.jpg" alt="" id="BLOGGER_PHOTO_ID_5585846595200180146" border="0" /></a><div style="text-align: center;"><span style="font-size:85%;"><span style="font-weight: bold;">The Moon looks extra-big when it is beaming through foreground objects--a.k.a. "the Moon illusion." Credit: NASA</span></span><br /></div><br />Dari perhitungan astronomi, pada tanggal 19 Maret 2011 Bulan dalam peredarannya mengelilingi Bumi, akan berada pada posisi paling dekat dengan Bumi, disebut sebagai posisi perigee. Tentunya dalam peredaran mengitari Bumi, Bulan akan selalui melalui posisi perigee, tetapi posisi perigee tersebut tidak selalu berada pada angka yang tepat sama, tetapi bervariasi sepanjang waktu.<br /><br />Pada tanggal tersebut, yang pada saat itu Bulan dalam fase Purnama, dalam perhitungan merupakan jarak yang paling dekat ke Bumi semenjak 18 tahun yang lalu. Lalu? Apa yang akan terjadi? Beredar kabar di dunia maya, bahwa pada saat tersebut, akan terjadi bencana alam yang sangat dahsyat, mulai dari badai besar, gempa Bumi sampai dengan letusan gunung berapi. Sepertinya seram sekali! Tetapi benarkah itu?<br /><br />Mari kita tinjau satu persatu, pertama, fenomena ‘supermoon’, ini sebetulnya adalah fenomena alam yang biasa terjadi. Pada suatu ketika, dalam peredarannya di langit, Bulan-Bumi-Matahari bisa berada dalam satu garis lurus, biasanya pada saat itu bisa terjadi bulan baru atau bulan purnama. Dan bila pada saat bulan purnama, Bulan berada pada posisi perigee, maka keadaan ini oleh para ahli astrologi (bukan ahli astronomi!) disebut ‘super moon’! Jadi istilah super moon bukanlah istilah astronomi, tetapi istilah astrologi.<br /><br />Kedua, pada tanggal itu, akan terjadi bencana alam? Tentulah dalam siklus alamiah, Bulan mempengaruhi terjadinya gaya pasang surut laut di Bumi, dan ketika Bulan ‘mendekat’, tentulah pengaruh gravitasi Bulan menjadi lebih besar (demikian yang dikatakan hukum gravitasi Newton). Akan tetapi, apakah bila pengaruh gravitasi Bulan menjadi lebih besar, akan terjadi bencana alam? Mari kita sedikit berhitung dengan matematika. Ambil rata-rata jarak Bumi-Bulan 382900 km, sedangkan pada tanggal 19 Maret 2011, Bumi-Bulan berjarak 356577 km, atau ‘mendekat’ sejarak 26323 km, atau hanya 6,87% lebih dekat dibanding rata-rata.<br /><br /></div><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8fJuTqYkv1Q_wNEovOji6O-ckix8j6pjv50vtiqqKKVa7AyZ8neHMxHPyyir_dY_as8K41MkPdpTg64ZpvybPy-KgWJreJFzq9WL5qu4dQYgKJJQHCMd0i9_I-2UQAf0rfrRf_-2IBjG3/s1600/superfullmoon.gif"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 229px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8fJuTqYkv1Q_wNEovOji6O-ckix8j6pjv50vtiqqKKVa7AyZ8neHMxHPyyir_dY_as8K41MkPdpTg64ZpvybPy-KgWJreJFzq9WL5qu4dQYgKJJQHCMd0i9_I-2UQAf0rfrRf_-2IBjG3/s400/superfullmoon.gif" alt="" id="BLOGGER_PHOTO_ID_5585848017733771954" border="0" /></a><span style="font-weight: bold;font-size:78%;" >Posisi Bulan saat berada di perigee atau titik terdekat dengan Bumi. courtsey</span><span style="font-weight: bold;font-size:78%;" > </span><a href="http://www.physorg.com/news/2011-03-super-full-moon.html"><span style="font-size:78%;"><span style="font-weight: bold;">physcorg.com</span></span></a><br /></div><div style="text-align: justify;"><br />Dengan jarak yang sekecil itu (6,87%), akan menyebabkan dampak yang luar biasa? Seperti biasa, efek pasang surut terjadi setiap hari, dan bila resultan vektor gaya gravitasi Bulan & Matahari menjadi lebih besar maka efek pasang surut menjadi lebih besar. Menurut physorg.com (yang mengutip NASA), efek "perigeean ides" ini hanya menambah tinggi air pasang beberapa cm saja (maximum 15 cm).<br /><br /></div><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6b1FpGDCbWE8PEIkC83NO05dhPx71trjay07VsJUll47V5iZlRVhIT0NI2HAd8wgpDIAaOa2hzEKFXgtL_mdCZGhUVa6FNz9mraCDPDryNEAah8RbFQ8Ao6v0YKVuxhjV96rTYSkpYauL/s1600/springneaptides1.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6b1FpGDCbWE8PEIkC83NO05dhPx71trjay07VsJUll47V5iZlRVhIT0NI2HAd8wgpDIAaOa2hzEKFXgtL_mdCZGhUVa6FNz9mraCDPDryNEAah8RbFQ8Ao6v0YKVuxhjV96rTYSkpYauL/s400/springneaptides1.jpg" alt="" id="BLOGGER_PHOTO_ID_5585844938413295154" border="0" /></a><span style="font-weight: bold;font-size:78%;" >Posisi Bumi-Bulan-Matahari dan kaitannya dengan pasang surut. kredit : Boomeria.org</span><br /></div><div style="text-align: justify;"><br />Tentunya pada saat ketika purnama ditambah perigee, gaya gravitasi menjadi lebih berpengaruh, tetapi, dari studi geofisika yang telah banyak dilakukan, tidak dtemukan adanya dampak yang signifikan pada keseimbangan energi Bumi. Gempa Bumi, letusan vulkanik, ataupun berbagai fenomena di Bumi lebih disebabkan keseimbangan energi di Bumi, seperti pergeseran lempeng Bumi, sedangkan efek pasang surut oleh Bulan, tidaklah cukup kuat menggeser keseimbangan energi tersebut, yang artinya ‘super moon’ tidak akan menyebabkan bencana alam.<br /><br />Mungkin dibutuhkan seorang Superman yang datang dari planet Kripton untuk menggeser keseimbangan Bumi, karena Superman mempunyai kekuatan yang jauh lebih besar dibanding kekuatan super moon; tetapi kita tahu bahwa superman adalah tokoh rekaan, sebagaimana bencana akibat super moon adalah telaah astrologi. Kalau sudah demikian, pertanyaan berikut, apa yang akan terjadi di tanggal 19 Maret yang akan datang?<br /><br />Yang pasti Bulan akan tampak lebih ‘besar’ 14% dan 30% lebih cerlang di Banding ‘biasanya’, namun bisakah Anda membedakannya (bukan karena Anda punya asumsi awal bahwa Bulan lebih besar dari biasanya)?<br /><br /><div style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8Y5ch_u-pgAaYS0tkM_fMkOTHqUT5rQa5YrPHUMdrAywv7axuSAgIaDzNL8KlSzLv6S7qnIthAa9H6UHT1OIMxDis1my4DDZvkjxWMmV1oM30tyR37ZCS8hRaa_Kk2HNxaqLx2dpHR8A5/s1600/supermoon.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 218px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8Y5ch_u-pgAaYS0tkM_fMkOTHqUT5rQa5YrPHUMdrAywv7axuSAgIaDzNL8KlSzLv6S7qnIthAa9H6UHT1OIMxDis1my4DDZvkjxWMmV1oM30tyR37ZCS8hRaa_Kk2HNxaqLx2dpHR8A5/s400/supermoon.jpg" alt="" id="BLOGGER_PHOTO_ID_5585844941438282898" border="0" /></a><span style="font-size:78%;"><span style="font-weight: bold;">Bulan Purnama saat di perigee akan tampak lebih besar 14%. kredit: NASA</span></span><br /><br /><div style="text-align: justify;">Jawabannya belum tentu. Di langit tidak ada penggaris/meteran yang dapat digunakan untuk mengukur diameter Bulan (selain Anda menggunakan teleskop dengan skala ukuran di lensa nya). Jika Anda mengamati Bulan saat di titik tertingginya dan tidak ada benda lain sebagai pembanding, maka Anda tidak dapat membedakan bulan purnama ini (super moon) dengan bulan purnama biasa.<br /><br />Untuk mendapatkan efek "piringan Bulan yang besar", Anda disarankan mengamati Bulan saat ada di dekat horizon. Pada posisi ini, ada efek ilusi optik yang akan menciptakan kesan bahwa piringan Bulan nampak lebih besar dari biasanya (efek ini terjadi pada saat gerhana Bulan "biasa" juga). Alasannya masih sulit dijelaskan oleh astronomer maupun psikolog. Bulan yang dekat dengan horizon akan nampak "sangat" besar (lihat ilustrasi gambar pertama).<br /></div><div style="text-align: justify;"><br />So, apakah fenomena supermoon penting untuk diamati? jawabnya tergantung Anda. Anda bisa memanfaatkan momentum ini untuk mengadakan observasi Bulan bersama teman Anda, baik dengan mengamati langsung maupun dengan binokular/teleskop kecil.<br /><br /><br /><span style="font-style: italic; color: rgb(0, 153, 0);">Artikel di atas disadur dari </span><a style="font-style: italic; color: rgb(0, 153, 0);" href="http://langitselatan.com/2011/03/18/menanti-indahnya-supermoon/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+langitselatan+%28langitselatan.com%29">Langit Selatan</a><span style="font-style: italic; color: rgb(0, 153, 0);"> dengan beberapa perubahan yang diambil dari </span><a style="font-style: italic; color: rgb(0, 153, 0);" href="http://www.physorg.com/news/2011-03-super-full-moon.html">physorg.com</a><span style="font-style: italic; color: rgb(0, 153, 0);">.</span><br /></div></div></div>Unknownnoreply@blogger.com5tag:blogger.com,1999:blog-7835130099283684649.post-20331414439750709132011-03-07T02:35:00.005+07:002011-03-07T02:45:33.294+07:00DocumentariesBeberapa kumpulan documentary yang menarik untuk disimak.<br /><br />1. Universe: The Cosmology Quest<br /><center><object height="259" width="425"><param name="movie" value="http://www.youtube.com/v/1yTfRy0LTD0&hl=en_US&feature=player_embedded&version=3"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/1yTfRy0LTD0&hl=en_US&feature=player_embedded&version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="259" width="425"></embed></object></center><br /><br />2. The Search for Life: The Drake Equation<br /><center><object height="259" width="425"><param name="movie" value="http://www.youtube.com/v/UzRirEcx-GQ&hl=en_US&feature=player_embedded&version=3"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/UzRirEcx-GQ&hl=en_US&feature=player_embedded&version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="259" width="425"></embed></object></center><br /><br />3. The Universe<br /><a href="http://topdocumentaryfilms.com/universe-season-1/">link</a><br /><br />4. How the Universe Works<br /><center><object height="259" width="425"><param name="movie" value="http://www.youtube.com/v/k8wI1I47vNI&hl=en_US&feature=player_embedded&version=3"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/k8wI1I47vNI&hl=en_US&feature=player_embedded&version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="259" width="425"></embed></object></center><br /><br />5. The Birth Of Earth<br /><center>Part 1<br /><embed id="VideoPlayback" src="http://video.google.com/googleplayer.swf?docid=-8905104227527404000&hl=en&fs=true" style="width: 400px; height: 326px;" allowfullscreen="true" allowscriptaccess="always" type="application/x-shockwave-flash"></embed><br /><br />Part 2<br /><embed id="VideoPlayback" src="http://video.google.com/googleplayer.swf?docid=-2925941239448817562&hl=en&fs=true" style="width: 400px; height: 326px;" allowfullscreen="true" allowscriptaccess="always" type="application/x-shockwave-flash"></embed><br /><br />Part 3<br /><embed id="VideoPlayback" src="http://video.google.com/googleplayer.swf?docid=2951465204497017576&hl=en&fs=true" style="width: 400px; height: 326px;" allowfullscreen="true" allowscriptaccess="always" type="application/x-shockwave-flash"></embed></center><br /><br />Semoga bermanfaatUnknownnoreply@blogger.com5tag:blogger.com,1999:blog-7835130099283684649.post-11507897457690658132011-02-09T06:49:00.003+07:002011-02-09T06:49:00.430+07:00Pseudoscience vs Science<div style="text-align: justify;"><span style="font-style: italic; color: rgb(255, 0, 0);">Akhir - akhir ini banyak sekali berita di media massa yang nampak seperti science namun sebenarnya hanya pseudo-science. Berikut ini ada artikel yang bagus mengenai hal ini, yang dikutip dari <a href="http://www.astronomynotes.com/pseudoscience.html">www.astronomynotes.com</a>.</span> <span style="font-style: italic; color: rgb(255, 0, 0);">Selamat membaca dan semoga bermanfaat.</span><br /></div><div style="text-align: justify;"><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBwdMS_54Sn_KfxuoTew0uuSrCPKrVOB3meTKyxJlL0rEvePTBa0PsJqOdl6q3bpoqL9mEFlfnREYWY2tLo7rT6KA2O4qEacRh2UkmJHDE_z0sQoCwrvTFvenJXLnFxFXQmC3q3xY3VHKO/s1600/iwanttobelieve.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 280px; height: 350px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBwdMS_54Sn_KfxuoTew0uuSrCPKrVOB3meTKyxJlL0rEvePTBa0PsJqOdl6q3bpoqL9mEFlfnREYWY2tLo7rT6KA2O4qEacRh2UkmJHDE_z0sQoCwrvTFvenJXLnFxFXQmC3q3xY3VHKO/s400/iwanttobelieve.jpg" alt="" id="BLOGGER_PHOTO_ID_5571116685930979122" border="0" /></a><br /> "Yes, the world <em>would</em> be a more interesting place if there were UFOs lurking in the deep waters off Bermuda and eating ships and planes, or if dead people could take control of our hands and write us messages. It would be fascinating if adolescents were able to make telephone handsets rocket off their cradles just be thinking at them, or if our dreams could, more often than can be explained by chance and our knowledge of the world, accurately foretell the future." Just one nice passage among many, many in Carl Sagan's "<a href="http://www.amazon.com/Demon-Haunted-World-Science-Candle-Dark/dp/0345409469/ref=sr_1_1?ie=UTF8&s=books&qid=1238654092&sr=8-1" target="outside">The Demon-Haunted World</a>" (available in the campus library and most public libraries). Well, Dr. Sagan, if the world would be more interesting if the unexplained UFOs were in fact space aliens, if we could communicate with the dead or space aliens, etc., why are you scientists such stuffy, party-poopers, insisting that the evidence is not good enough to prove that these things exist? With <em>thousands</em> of eye-witnesses, what more do you need? Sagan wrote that passage above just before he discussed <em>pseudoscience</em> in "<a href="http://search.barnesandnoble.com/The-Demon-Haunted-World/Carl-Sagan/e/9780345409461/?itm=1" target="outside">The Demon-Haunted World</a>". If we understand the difference between real science and pseudoscience, perhaps we can understand the view of many scientists and skeptics that the UFO research is pseudoscience.<br /><br /> <span style="font-weight: bold; color: rgb(255, 0, 0);"> "Pseudo" means "not genuine; sham", something pretending to be something else that it is not</span>. <span style="font-weight: bold; color: rgb(0, 0, 153);">Pseudosciences "purport to use the methods and findings of science, while in fact they are faithless to its nature—often because they are based on insufficient evidence or because they ignore clues that point the other way</span>" (Sagan, 1996). <span style="color: rgb(255, 102, 0); font-weight: bold;">We are awash in pseudoscience from all around us because "pseudoscience is easier to contrive than science</span>" ("contrive" is a pretty strong word choice by Dr. Sagan). With pseudoscience, the standards of argument and what is allowable as evidence are much more relaxed than what you find in science.<br /><br /> <span style="font-weight: bold; color: rgb(51, 204, 0);">This is not to say that all of science is correct</span>. No, there have been plenty of mistakes in science, plenty of blind alleys. No, reality is messier, more unpredictable than the best detective/murder-mystery novel. With science, hypotheses are framed in a way that they can be tested by experiment and observation. <span style="font-weight: bold; color: rgb(51, 204, 0);">Nature has the final veto power in whatever explanation we come up with but scientists are human (yes, they are) and subject to emotional attachments to their explanations.</span> They too can be offended when their pet explanation doesn't pan out, when Nature has vetoed it.<br /><br /> <span style="font-weight: bold; color: rgb(204, 153, 51);">Pseudoscience is just the opposite. Hypotheses are often framed in a way that makes them untestable</span>. "Practitioners [of pseudoscience] are defensive and wary. Skeptical scrutiny is opposed. When the pseudoscientific hypothesis fails to catch fire with scientists, conspiracies to suppress it are deduced" (Sagan, 1996). Ah, yes! How many times have we heard that the science journals won't publish the UFO research with charges of bias and close-mindedness on the part of the science "establishment"? Such charges are part of the conspiracy mindset. I'm sorry, but it is not a conspiracy. It is because the UFO evidence is not of the caliber needed to base conclusions upon and less fantastic alternative explanations that don't involve space aliens are not addressed or explored by the author of the proposed paper. Not every truly scientific paper makes it into the journals either but the scientist doesn't complain of a conspiracy. No, the paper was probably rejected because more data needed to be gathered to improve the signal (the confidence level) above the ever-present statistical fluctuations of reality in order to deduce the conclusion reached by the author. Sometimes, too strong a conclusion is deduced from too weak a data set. Another likelihood is that the author did not explore an alternative explanation because they failed to see the assumptions that they were operating under. Our filters can blind us to the obvious.<br /><br /> "<span style="font-weight: bold; color: rgb(255, 0, 0);">Perhaps the sharpest distinction between science and pseudoscience is that science has a far keener appreciation of human imperfections and fallibility than does pseudoscience</span>." (Sagan, 1996) <span style="font-weight: bold; color: rgb(51, 204, 0);">This is why conclusions based solely (or even mostly) on eye-witness testimony are not acceptable in science, however harsh that may seem to the layman</span>. The Innocence Project (see <a href="http://www.innocenceproject.org/">www.innocenceproject.org</a>) has shown that eyewitness identification has played a significant role in 75% of the convictions that were later overturned through DNA testing. Thirty years of social science research has proven that eyewitness identification is often unreliable. Even victims of horrendous personal crimes have mis-identified the perpetrators. Unfortunately, our memories are malleable. Initial uncertainties in recollection become strongly-held beliefs, bed-rock certainties, once we've had time to try to make sense of what happened. Our creativity can sometimes lead us astray. It can happen to the best of us. Even scientists. Please see <a href="http://www.theinvisiblegorilla.com/" target="outside">Christopher Chabris' and Daniel Simons' Invisible Gorilla website</a> for some of this research and especially see Dan Simons' "Counter-Intuition" talk he gave in April 2010. There is a <a href="http://www.youtube.com/watch?v=eb4TM19DYDY&feature=player_embedded" target="outside">video of his short talk</a> in the video section of Invisible Gorilla in which he gives powerful examples of our perceptions, intuitions, and even the reasoning about our intuition leading even the best of observers astray. That is why scientists lay their results open to the very critical scrutiny of others. And they agree to accept the criticism and re-submit their work when they have improved their argument through better data or give it up when the observations show that their idea does not have merit. They don't blame the "establishment".<br /><br /> So, it is not because scientists just don't want to believe in space aliens that they are critical of the claims of UFOs as aliens, it is because time and time again the <em>methodology</em> of the UFO claims have not followed the high standards of verifiable scientific research. Has every claim of UFOs-as-space aliens been investigated? No. There are so many! It takes more time and energy to figure out the ordinary, natural cause of something than it takes for creative people to imagine fantastic things. Perhaps scientists are a bit too quick to discount UFOs-as-space aliens claims but after years of going down that dead end interpretation of noisy data, can you understand why they might want to devote their time to something more provable?<br /><br /> The next several pages are lengthy excerpts of Sagan's <a href="http://catalog.loc.gov/cgi-bin/Pwebrecon.cgi?DB=local&BBID=3506635&v3=1" target="outside">"The Demon-Haunted World: Science as a Candle in the Dark", published by Ballantine Books (New York) in 1996 (ISBN 0-345-40946-9)</a>. These excerpts are examples of alternative, plausible explanations that "point the other way" from that of space aliens and government cover-ups of space alien invasions. <h2>Roswell, New Mexico</h2> <p> What follows is an excerpt from Sagan's "<a href="http://www.powells.com/biblio/1-9780345409461-6" target="outside">The Demon-Haunted World</a>" <span style="font-weight: bold; color: rgb(255, 0, 0);">about the alleged flying saucer crash in Roswell</span>, NM in 1947 (page 84-86).</p><p><br /> A great to-do has been made of one or more alleged crashed flying saucers near Roswell, New Mexico, in 1947. Some initial reports and newspaper photographs of the incident are entirely consistent with the idea that the debris was a crashed high-altitude balloon. But other residents of the region—especially decades later—remember more exotic materials, enigmatic hieroglyphics, threats by military personnel to witnesses if they didn't keep what they knew to themselves, and the canonical story that alien machinery and body parts were packed into an airplane and flown to the Air Materiel Command at Wright-Patterson Air force Base. Some, but not all, of the recovered alien body stories are associated with this incident.</p><p><br /> Philip Class, a long-time and dedicated UFO skeptic, has uncovered a subsequently declassified letter dated July 27, 1948, a year after the Roswell" incident," from Major General C.B. Cabell—then Director of Intelligence for the U.S. Air Force (and later, as a CIA offical, a major figure in the abortive U.S. invasion of Cuba at the Bay of Pigs). Cabell was inquiring of those who reported to him on what UFOs might be. He hadn't a clue. In an October 11, 1948 summary response, explicitly including information in the possession of the Air Materiel Command, we find the Director of Intelligence being told that nobody else in the Air Force had a clue either. This makes it unlikely that UFO fragments and occupants had made their way to Wright-Patterson the year before.</p><p><br /> What the Air Force was mostly worried about was that UFOs were Russian. Why Russians would be testing flying saucers over the United States was a puzzle to which the following four answers were proposed: "(1) To negate U.S. confidence in the atom bomb as the most advanced and decisive weapon in warfare. (2) To perform photographic reconnaissance missions. (3) To test U.S. air defenses. (4) To conduct familiarization flights [for strategic bombers] over U.S. territory." We now know that UFOs neither were or are Russian, and however dedicated the Soviet interest may have been to objectives (1) through (4), flying saucers weren't how they pursued these objectives.</p><p><br /> Much of the evidence regarding the Roswell "incident" seems to point to a cluster of high-altitude classified balloons, perhaps launched from nearby Alamogordo Army Air Field or White Sands Proving Ground, that crashed near Roswell, the debris of secret instruments hurriedly collected by earnest military personnel, early press reports announcing that it was a spaceship from another planet ("RAAF Captures Flying Saucer on Ranch in Roswell Region"), diverse recollections simmering over the years, and memories refreshed by the opportunity for a little fame and fortune. (Two UFO museums in Roswell are leading tourist stops.)<br /> A 1994 report ordered by the Secretary of the Air Force and the Department of Defense in response to prodding from a New Mexico Congressman identifies the Roswell debris as remnants of a long-range, highly secret, balloon-borne low-frequency acoustic detection system call "Project Mogul"—an attempt to sense Soviet nuclear weapons explosions at tropopause altitudes. The Air Force investigators, rummaging comprehensively through the secret files of 1947, found no evidence of heightened message traffic:</p><p><br /> There were no indications and warnings, notice of alerts, or a higher tempo of operational activity reported that would be logically generated if an alien craft, whose intentions were unknown, entered U.S. territory…The records indicated that none of this happened (or if it did, it was controlled by a security system so efficient and tight that no one, U.S. or otherwise, has been able to duplicate it since. If such a system had been in effect at the time, it would have also been used to protect our atomic secrets from the Soviets, which history has shown obviously was not the case.)</p><p><br /> The radar targets carried by the balloons were partly manufactured by novelty and toy companies in New York, whose inventory of decorative icons seems to have been remembered many years later as alien hieroglyphics.</p><p><br /> <em>In an earlier passage Sagan notes that balloons were extensively used by the Air Force in the 1950s for various uses including robotic espionage craft, with high-resolution cameras and signal intelligence devices. </em>"High-altitude balloons can seem saucer-shaped when seen from the ground. If you misestimate how far away they are, you can easily imagine them going absurdly fast. Occasionally, propelled by a gust of wind, they make abrupt changes in direction, uncharacteristic of aircraft and in seeming defiance of the conservation of momentum—if you don't realize that they're hollow and weigh almost nothing." (p. 83) <em>Please remember this when you read about reports of alien craft capable of accelerations and sudden changes of trajectory that are impossible with modern aircraft and would create fatal g-forces for humans.</em></p> <h2>Spoofing</h2> <p> Another excerpt from Sagan's "The Demon-Haunted World" that gives a plausible explanation of the unknown radar events during the Cold War that were kept under wraps (p. 86-87):</p><p><br /> Consider spoofing. In the strategic confrontation between the United states and the Soviet Union, the adequacy of air defenses was a vital issue. It was item (3) on General Cabell's list. If you could find a weakness, it might be the key to "victory" in an all-out nuclear war. The only sure way to test your adversary's defenses is to fly an aircraft over their borders and see how long it takes for them to notice. The United States did this routinely to test Soviet air defenses.</p><p><br /> In the 1950s and ‘60s, the United States had state-of-the-art radar defense systems covering its west and east coats, and especially its northern approaches (over which a Soviet bomber or missile attack would most likely come). But there was a soft underbelly—no significant early warning system to detect the geographically much more taxing southern approach. This is of course information vital for a potential adversary. It immediately suggests a spoof: One or more of the adversary's high-performance aircraft zoom out of the Caribbean, let's say, into U.S. airspace, penetrating, let's say, a few hundred miles up the Mississippi River until a U.S. air defense radar locks on. Then the intruders hightail it out of there. (Or, as a control experiment, a unit of U.S. high-performance aircraft is sequestered and sent in unannounced sorties to determine how porous American air defenses are.) In such a case, there may be combined visual and radar sightings by military and civilian observers and large numbers of independent reports. What is reported corresponds to no known aircraft. The Air Force and civilian aviation authorities truthfully state that none their aircraft was responsible. Even if they've been urging Congress to fund a southern Early Warning System, the Air Force is unlikely to admit that Soviet or Cuban aircraft got to New Orleans, much less Memphis, before anybody caught on.</p><p><br /> Here again, we have every reason to expect a high-level technical investigating team, Air Force and civilian observers told to keep their mouths shut, and not just the appearance but the reality of suppression of data. Again, this conspiracy of silence need have nothing to do with alien spacecraft. Even decades later, there are bureaucratic reasons for the Department of Defense to be close-mouthed about such embarrassments. There is a potential conflict of interest between parochial concerns of the Department of Defense and the solution of the UFO enigma.</p> <h2>Government Conspiracies</h2> One last excerpt from Sagan's "The Demon-Haunted World" about oft-lodged charge of the government's conspiracy of silence (p. 92-93). (Any more excerpts and I'll surely be charged with copyright infringement—please read the book for more! Though much lengthier excerpts are available for free on the <a href="http://books.google.com/books?id=q_Fp3tjPnkwC&dq=Carl+Sagan&printsec=frontcover&source=an&hl=en&ei=wV7USen3Mo-6tQOSqtytCg&sa=X&oi=book_result&ct=result&resnum=9#PPA99,M1" target="outside">Google Books version</a>...)<br /><br /> A cover-up to keep knowledge of extraterrestrial life or alien abductions almost wholly secret for 45 years, with hundreds if not thousands of government employees privy to it, is a remarkable notion. Certainly, government secrets are routinely kept, even secrets of substantial general interest. But the ostensible point of such secrecy is to protect the country and its citizens. Here, though, it's different. The alleged conspiracy of those with security clearances is to keep from the citizens knowledge of a continuing alien assault on the human species. If extraterrestrials really were abducting millions of us, it would be much more than a matter of national security. It would impact the security of all human beings everywhere on Earth. Given such stakes, is it plausible that no one with real knowledge and evidence, in nearly 200 nations, would blow the whistle, speak out and side with the humans rather than the aliens?<br /><br /> Since the end of the Cold War NASA has been flailing about, trying to find missions that justify its existence—particularly a good reason for humans in space. If the Earth were being visited daily by hostile aliens, wouldn't NASA leap on this opportunity to augment is funding? And if an alien invasion were in progress, why would the Air Force, traditionally led by pilots, step back from manned spaceflight and launch all its payloads on unmanned boosters?<br /><br /> Consider the former Strategic Defense Initiative Organization, in charge of "Star Wars." It's fallen on hard times now <em>[in 1996]</em>, particularly its objective of basing defenses in space. Its name and perspective have been demoted. It's the Ballistic Missile Defense Organization these days. It no longer even reports directly the Secretary of Defense. The inability of such technology to protect the United States against a massive attack by nuclear-armed missiles is manifest. But wouldn't we want at least to attempt deployment of defenses in space if we were facing an alien invasion?<br /><br /> The Department of Defense, like similar ministries in every nation, thrives on enemies, real or imagined. It is implausible in the extreme that the existence of such an adversary would be suppressed by the very organization that would most benefit from its presence. The entire post-Cold War posture of the military and civilian space programs of the United States (and other nations) speaks powerfully against the idea that there are aliens among us—unless, of course, the news is also being kept from those who plan the national defense. <em>[No, please don't take the bait dangling in that last sentence…]</em><br /></div>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-7835130099283684649.post-70057088866410834302011-02-08T06:15:00.001+07:002011-02-08T06:15:00.385+07:00A Brief History of Observing the Sun<center><object style="height: 256px; width: 420px;"><param name="movie" value="http://www.youtube.com/v/G8JymP6hxoA?version=3"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/G8JymP6hxoA?version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="256" width="420"></embed></object></center><p>A little history of sun-watching and science from our friends at the Solar Dynamics Observatory.</p><p>Source: <a href="http://www.universetoday.com/83119/a-brief-history-of-observing-the-sun/">Universe Today</a><br /></p>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-48916718375051382462011-02-07T16:50:00.020+07:002011-02-07T21:13:41.387+07:00Definisi Planet - Mengapa Pluto tidak termasuk kategori Planet?<div style="text-align: justify;">Mungkin beberapa tahun lalu, jumlah planet yang kita kenal ada 9, yaitu: Merkurius, Venus, Bumi, Mars, Jupiter, Saturnus, Uranus, Neptunus dan Pluto. Namun, tahukah Anda bahwa pada tahun 2006, International Astronomical Union (IAU) telah menentukan definisi planet yang baru. Imbas dari definisi planet yang baru ini sangat besar, karena Pluto yang sudah familiar dikenal sebagai sebuah planet akhirnya harus tersingkir dari "gelar"-nya. Tahukah Anda mengapa Pluto akhirnya "tersingkir"?<br /></div><div style="text-align: justify;"><br />Planet, secara etimologis berarti pelancong (wanderer). Pada akhir abad ke-19, istilah Planet sudah menjadi istilah umum, meskipun belum ada batasan yang jelas mengenai kriteria suatu benda yang dapat dianggap sebagai planet. Umumnya, istilah "planet" diberikan kepada objek yang mengitari Matahari dan berukuran lebih besar daripada Pluto.<br /><br />Setelah tahun 1992, astronomer telah menemukan banyak objek di luar orbit Neptunus (dikenal dengan istilah Trans-Neptunian Objects atau TNO) dan ratusan objek yang mengitari bintang lain (extrasolar planet, lihat artikel sebelumnya). Penemuan ini tidak hanya menambah jumlah dr objek yang potensial disebut planet, tetapi juga memperluas kenaekaragaman dan keanehan (peculiarity) dari objek-objek yang "masuk" kategori planet berdasarkan definisi/pengertian umum. Beberapa objek yang ditemukan tersebut ada yang lebih kecil daripada satelit Bumi, Bulan dan ada juga yang cukup besar untuk menjadi sebuah bintang. Penemuan - penemuan inilah yang membuat astronom merasa adanya kebutuhan untuk menentukan definisi dari sebuah Planet secara jelas agar tidak sembarang objek bisa dianggap sebagai planet.<br /><br /><div style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/8/81/Outersolarsystem_objectpositions_labels_comp.png"><img style="width: 400px; height: 400px;" alt="File:Outersolarsystem objectpositions labels comp.png" src="http://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Outersolarsystem_objectpositions_labels_comp.png/611px-Outersolarsystem_objectpositions_labels_comp.png" /></a><br /><span style="font-size:85%;"><span style="font-style: italic; font-weight: bold;">Plot of the positions of all known </span><a style="font-style: italic; font-weight: bold;" href="http://en.wikipedia.org/wiki/Kuiper_belt_object" title="Kuiper belt object" class="mw-redirect">Kuiper belt objects</a><span style="font-style: italic; font-weight: bold;"> (green), set against the outer planets (blue)</span></span><br /></div><br />Perlunya definisi yang jelas untuk Planet menjadi semakin jelas ketika ditemukannya TNO yang diberi nama <a href="http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29">Eris</a>. Ukuran Eris lebih besar daripada ukuran Pluto, yang sebelumnya dianggap sebagai ukuran minimum untuk sebuah planet. Oleh sebab itu, pada bulan Agustus 2006, International Astronomical Union (IAU) mengadakan konferensi untuk membuat definisi baru Planet.<br /><div style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Eris_and_dysnomia2.jpg/220px-Eris_and_dysnomia2.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 220px; height: 219px;" src="http://upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Eris_and_dysnomia2.jpg/220px-Eris_and_dysnomia2.jpg" alt="" border="0" /></a><span style="font-size:85%;"><a href="http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29" title="Eris (dwarf planet)"><span style="font-style: italic;"><span style="font-weight: bold;">Eris</span></span></a><span style="font-style: italic; font-weight: bold;"> as seen with the Hubble Space Telescope</span><br /></span></div><span style="font-weight: bold; color: rgb(255, 0, 0);"><br />DEFINISI PLANET BERDASARKAN IAU TAHUN 2006</span><br /><p>The final definition, as passed on 24 August 2006 under the Resolution 5A of the 26th General Assembly is:</p><div style="text-align: center;"><a href="http://en.wikipedia.org/wiki/File:ThePlanetDefinition3.png" class="image"><img style="width: 406px; height: 215px;" alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/ThePlanetDefinition3.png/500px-ThePlanetDefinition3.png" class="thumbimage" /></a><br /><div style="text-align: justify;"><div style="text-align: center;"><span style="font-size:85%;"><span style="font-style: italic; font-weight: bold;">Illustration of the outcome of the vote</span></span><br /><br /></div><span style="color: rgb(0, 0, 153);">The IAU resolves that planets and other bodies, except satellites, in our Solar System be defined into three distinct categories in the following way:</span><br /><br /><span style="color: rgb(204, 0, 0);">(1) A planet [1] is a celestial body that:<br /></span><ul style="color: rgb(204, 0, 0);"><li><span style="color: rgb(204, 0, 0);">(a) is in orbit around the Sun, </span></li><li><span style="color: rgb(204, 0, 0);">(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and </span></li><li><span style="color: rgb(204, 0, 0);">(c) has cleared the neighbourhood around its orbit.</span></li></ul><span style="color: rgb(102, 0, 204);">(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.</span><br /><br /><span style="color: rgb(153, 51, 0);">(3) All other objects [3], except satellites, orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".</span><br /><br /><span style="color: rgb(204, 0, 0);font-size:85%;" >Footnotes:</span><span style="font-size:85%;"><br /></span><span style="color: rgb(204, 0, 0);font-size:85%;" >[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.</span><span style="font-size:85%;"><br /></span><span style="color: rgb(204, 0, 0);font-size:85%;" >[2] An IAU process will be established to assign borderline objects into either dwarf planet and other categories.</span><span style="font-size:85%;"><br /></span><span style="color: rgb(204, 0, 0);font-size:85%;" >[3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.</span><span style="font-size:85%;"><br /><br /></span><span style="color: rgb(0, 0, 0);font-size:100%;" >The IAU further resolves:</span><span style="color: rgb(0, 0, 0);font-size:100%;" ><br /></span><span style="color: rgb(0, 0, 0);font-size:100%;" >Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of Trans-Neptunian Objects[1].</span><span style="color: rgb(0, 0, 0);font-size:100%;" ><br /></span><span style="color: rgb(0, 0, 0);font-size:85%;" ><br /></span><span style="color: rgb(0, 0, 0);font-size:85%;" >Footnote:</span><span style="color: rgb(0, 0, 0);font-size:85%;" ><br /></span><span style="color: rgb(0, 0, 0);font-size:85%;" >[1] An IAU process will be established to select a name for this category.</span><span style="color: rgb(0, 0, 0);font-size:85%;" ><br /></span><span style="color: rgb(0, 0, 0);font-size:85%;" >The IAU also resolved that "planets and dwarf planets are two distinct classes of objects", meaning that dwarf planets, despite their name, would not be considered planets</span><br /></div>.<br /><div style="text-align: justify;">Penjelasan di atas adalah bunyi dari keputusan IAU mengenai definisi Planet yang baru. <span style="font-weight: bold;">Secara sederhana, syarat- syarat sebuah objek dapat dikategorikan sebagai planet dalam tata surya ini jika:</span><br /></div><ol style="text-align: justify;"><li style="font-weight: bold; color: rgb(255, 0, 0);">mengitari Matahari</li><li style="font-weight: bold; color: rgb(0, 0, 153);">memiliki massa yang cukup untuk mencapai kondisi <a href="http://en.wikipedia.org/wiki/Hydrostatic_equilibrium">k</a><a href="http://en.wikipedia.org/wiki/Hydrostatic_equilibrium"></a><a href="http://en.wikipedia.org/wiki/Hydrostatic_equilibrium">esetimbangan hidrostatis</a> (secara sederhana, objek yang sudah mencapai kondisi kesetimbangan hidrostatis memiliki bentuk bola sempurna).</li><li><span style="color: rgb(0, 153, 0); font-weight: bold;">telah "<a href="http://en.wikipedia.org/wiki/Clearing_the_neighbourhood">membersihkan objek-objek tetangga</a>" dari orbitnya. atau dengan kata lain, massa Planet adalah massa yang dominan dibandingkan massa seluruh benda lain yang berada di orbit yang sama.</span><br /></li></ol><div style="text-align: justify;">Sebuah objek yang tidak termasuk satelit dan hanya memenuhi dua syarat pertama akan diklasifikasikan sebagai <a href="http://en.wikipedia.org/wiki/Dwarf_planet">dwarf planet</a> (planet kerdil). Bagi objek yang hanya memenuhi syarat pertama (mengitari Matahari), akan disebut <a href="http://en.wikipedia.org/wiki/Small_solar_system_body">Small Solar System Body</a> (SSSB) atau objek kecil di tata surya. Draft awal merencanakan akan memasukkan dwarf planet sebagai sub-kategori dari planet, tetapi karena keputusan ini akan mengakibatkan penambahan beberapa lusin objek ke dalam tata surya, draft ini dibatalkan. Di tahun 2006, yang termasuk dwarf planet adalah <a href="http://en.wikipedia.org/wiki/Ceres_%28dwarf_planet%29" title="Ceres (dwarf planet)">Ceres</a>, <a href="http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29" title="Eris (dwarf planet)">Eris</a>, <a href="http://en.wikipedia.org/wiki/Makemake_%28dwarf_planet%29" title="Makemake (dwarf planet)">Makemake</a>, dan <a href="http://en.wikipedia.org/wiki/Pluto">Pluto</a>. Keputusan ini termasuk keputusan yang kontroversial dan menimbulkan dukungan dan kritik dari cukup banyak astronom, tetapi definisi inilah yang dipakai resmi hingga saat ini.<br /><br />Jad, berdasarkan definisi yang baru ini, saat ini ada 8 planet yang diakui (Merkurius, Venus, Bumi, Mars, Jupiter, Saturnus, Uranus, dan Neptunus) dan ada <a href="http://en.wikipedia.org/wiki/Dwarf_planet#Current_members">lima planet kerdil</a> (Pluto, Ceres, Eris, Makemake, dan Haumea). Definisi ini hanya berlaku untuk Tata Surya kita karena extrasolar Planet belum diketahui dengan jelas/akurat ukurannya. Extrasolar planets atau exoplanets akan didefinisikan dalam referensi lain, yang memisahkan/membedakan exoplanet dan dwarf stars (bintang kerdil).<br /></div><div style="text-align: justify;"><br />Pertanyaan evaluasi:<br />1. Mengapa perlu adanya definisi baru untuk Planet?<br />2. Jelaskan definisi baru/syarat-syarat sebuah objek dijadikan Planet? Planet Kerdil?<br /></div></div></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-3764753964849655502011-02-04T17:25:00.052+07:002011-02-07T16:50:17.927+07:00Mendeteksi dan Menemukan Extrasolar Planet<div style="text-align: justify;">Belakangan ini banyak dibahas di berbagai media tentang penemuan planet di tata surya lain. Dalam artikel ini, akan dibahas beberapa teknik 'sederhana' yang digunakan astronom untuk menemukan planet di luar tata surya.<br /></div><div style="text-align: justify;"><br />Seperti yang Anda ketahui bahwa bintang akan selalu terlihat sebagai point of light (sumber titik cahaya) meskipun menggunakan teleskop (kecuali untuk beberapa bintang yang besar dan 'dekat' dengan kita). Oleh sebab itu, dapat diperkirakan bahwa mengamati planet yang ada di bintang lain tentunya bukan perkara yang mudah.<br /><br />Sebelum kita membahas bagaimana menemukan planet extrasolar (planet yang ada di luar tata surya kita), akan dibahas terlebih dahulu sekilas mengenai proses pembentukan planet.<br /><br /><span style="font-weight: bold; color: rgb(0, 0, 153);">SEJARAH SINGKAT TERBENTUKNYA PLANET</span><br /><br />Semuanya berawal dari material awan debu. Tata surya (planetary system/sistem keplanetan) berasal dari awan berputar yang maha besar. Awan kabut itu (nebulae) mengerut di bawah gaya berat diri, membentuk piringan dengan protosurya yang sangat padat di pusat. Akibat pengerutan gravitasi suhu naik di dalam awan (<span style="font-style: italic; font-weight: bold; color: rgb(204, 0, 0);">pengerutan Kelvin Helmholtz</span>). Di pusat kian sangat panas, lalu terpicu reaksi bom nuklir, dan pengerutan piringan akan berhenti.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEUMpdqOM85LDxr9demf2PPAypiYRH21HJ-DTvAQkLKH667WKOd1cjpIO3Or6tK6NTKcsO709lB7AhjfCzzpVFCWs7cHnZJGMXUKhVKhqUIKiijEOnhzxC6FUHntqzBZULjrxjLSPMtZ6D/s1600/slide0009_image037.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 296px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEUMpdqOM85LDxr9demf2PPAypiYRH21HJ-DTvAQkLKH667WKOd1cjpIO3Or6tK6NTKcsO709lB7AhjfCzzpVFCWs7cHnZJGMXUKhVKhqUIKiijEOnhzxC6FUHntqzBZULjrxjLSPMtZ6D/s400/slide0009_image037.jpg" alt="" id="BLOGGER_PHOTO_ID_5569780538008029298" border="0" /></a>Planet-planet terbentuk oleh akresi planetesimal dan akumulasi gas di dalam kabut surya. Planetesimal di tahap awal tatasurya, tabrakan dan akresi (saling menempel) membentuk <span style="font-weight: bold; color: rgb(0, 153, 0);">protoplanet</span>. Planet dari unsur-unsur berat terbentuk dan memadat di bagian dalam, suhu jadi lebih panas (di pusat), unsur-unsur ringan berdifusi ke tepi luar. Proses itu dikenal sebagai <span style="font-weight: bold; color: rgb(0, 153, 0);">diferensiasi dari unsur-unsur</span>.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHBR1OIKBEhRvCcbIOBcXiKrHq90lazcHJfWauI5KPEvJqVV8hB9IDFz63W8LvB1uezJsLtHfB7nBNXwVY_h-FN7TA2_vA4Xce791Va-n3-Kmkf9JGBKEwTG-oLDp8mJ2JXOedzcpqMpqH/s1600/Picture1.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 82px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHBR1OIKBEhRvCcbIOBcXiKrHq90lazcHJfWauI5KPEvJqVV8hB9IDFz63W8LvB1uezJsLtHfB7nBNXwVY_h-FN7TA2_vA4Xce791Va-n3-Kmkf9JGBKEwTG-oLDp8mJ2JXOedzcpqMpqH/s400/Picture1.jpg" alt="" id="BLOGGER_PHOTO_ID_5569782952254257202" border="0" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-bUOotw24dBtezg1lqOAuTyeW_Ooy4nUKKuDwnIrbLixGwjAxzUhP1ZvVeI7Uc9MHBYMEcibKI5P_X96CIfwSNxlg6m3DptfEH0ByGCuAaEi2V-v9usDxvu9BLSxoBGu6zQ-P4Wq64tZf/s1600/slide0028_image058.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 296px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-bUOotw24dBtezg1lqOAuTyeW_Ooy4nUKKuDwnIrbLixGwjAxzUhP1ZvVeI7Uc9MHBYMEcibKI5P_X96CIfwSNxlg6m3DptfEH0ByGCuAaEi2V-v9usDxvu9BLSxoBGu6zQ-P4Wq64tZf/s400/slide0028_image058.jpg" alt="" id="BLOGGER_PHOTO_ID_5569803859053943042" border="0" /></a><br />Bintang yang masih muda (yang terbentuk di pusat akresi) tiba-tiba menyemburkan tenaga kuat, tenaga jet dan sangat singkat, dan membersihkan tata surya dari materi pembentuk planet yang tersisa. Bintang-bintang muda penyembur tenaga semacam itu dikenal sebagai <span style="font-weight: bold; color: rgb(255, 0, 0);">Bintang-Bintang T Tauri </span>.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4nu6mfKv1R1oB4TWhAOipMBhEAqhRLP4KSJSc3ZpVyyGfyn9Jz9TRcX9Kp53_z4OPUegMWGX1288WXWuOj15dPeCy1DPtuCkbChDNif-tvXh_L14RYGfrM_D19pl5CNb_6loaUXVTXkn2/s1600/slide0070_image058.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 220px; height: 220px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4nu6mfKv1R1oB4TWhAOipMBhEAqhRLP4KSJSc3ZpVyyGfyn9Jz9TRcX9Kp53_z4OPUegMWGX1288WXWuOj15dPeCy1DPtuCkbChDNif-tvXh_L14RYGfrM_D19pl5CNb_6loaUXVTXkn2/s400/slide0070_image058.jpg" alt="" id="BLOGGER_PHOTO_ID_5569783600065510210" border="0" /></a>Setelah itu, tata surya akan 'stabil'. Planet - planet butuh jutaan tahun untuk menggumpal dan membersihkan 'orbit'-nya serta mendingin hingga mencapai kondisi stabil.<br /><br /><span style="font-weight: bold; color: rgb(0, 0, 153);">PLANET DI TATA SURYA LAIN (EXTRASOLAR PLANETS)</span><br /><br />Para astronom telah menemukan planet-planet mengorbit di bintang-bintang. Planet besar, seperti Yupiter, menarik bintang pusatnya ke dalam sehingga bintang terputar dalam satu orbit kecil mengitari titik pusat massa mereka. Planet yang mengorbit bintang lain itu disebut <span style="font-style: italic; font-weight: bold; color: rgb(255, 0, 0);">extrasolar planets</span>.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwO7JIYXz0Q_Qj7Szqy-dBpYpFOIUEOkJoY14XAFo9A2cL4c4I_fsXcOWMAgMOzJptQEdMWvhBXbCuID2kvJyLhjEa88zWTdQKy7OvlSkpP58X3HWIcablKwModZIRBc6u2aJYCrGslCbX/s1600/Picture2.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 141px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwO7JIYXz0Q_Qj7Szqy-dBpYpFOIUEOkJoY14XAFo9A2cL4c4I_fsXcOWMAgMOzJptQEdMWvhBXbCuID2kvJyLhjEa88zWTdQKy7OvlSkpP58X3HWIcablKwModZIRBc6u2aJYCrGslCbX/s400/Picture2.jpg" alt="" id="BLOGGER_PHOTO_ID_5569785768012088930" border="0" /></a>Meski Planet sangat besar, tetap tak bisa dilihat, karena bintang sentral sangat terang. Namun, pergerakan kecil yang ditempuh bintang sentral karena gravitasi oleh planet, kadangkala dapat terdeteksi. Para astronom mengukur dengan teliti pergerakan bintang dengan memperhatikan sinarnya. Sinar bintang itu bergantian bergeser ke riak gelombang merah dan ke riak gelombang biru. Telah terdeteksi dengan cara itu lebih dari 100 extrasolar planet. Cara itu dikenal sebagai metode <span style="font-weight: bold; color: rgb(0, 153, 0);">Pergeseran Doppler</span>.<br /><br />Beberapa planet yang sudah ditemukan:<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE7pcvZapc1SRgCslVIxRzRDy6lFYnodB-YDnaIR-E0jdFPavouF-SCTzD1AkLwGheTGtquyObXwcKELq5nItpOffgBE9moWqpbx2fDQbnfvunOiy_GujAq5uwfKE5_l8zChsXZgjv7hBO/s1600/slide0033_image013.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 275px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE7pcvZapc1SRgCslVIxRzRDy6lFYnodB-YDnaIR-E0jdFPavouF-SCTzD1AkLwGheTGtquyObXwcKELq5nItpOffgBE9moWqpbx2fDQbnfvunOiy_GujAq5uwfKE5_l8zChsXZgjv7hBO/s400/slide0033_image013.jpg" alt="" id="BLOGGER_PHOTO_ID_5569787129940329714" border="0" /></a><br />OGLE-2005-BLG-390Lb planet extrasolar terkecil saat ini (2006). 188 extrasolar planet (18 April 2006) berbagai rentang massa dan periode orbit, namun planet sebesar massa Neptunus sangat sedikit/belum terdeteksi pada jarak > 0,15 SA dari bintang pusat. OGLE-2005-BLG-390Lb bermassa 5,5 (-2,7 to +5,5) massa bumi. Pada jarak pisah 2,6(-0,6 to +1,5) SA dari bintang kerdil-M bermassa 0,22(-0,11 to +0,21) massa matahari (68% rentang kepastian). Teori akresi planet meramalkan banyak planet bermassa lebih kecil daripada planet Neptunus ditemukan daripada planet raksasa Jupiter.<br /><br />Jadi, ada banyak metode yang dapat digunakan oleh astronom untuk mendeteksi keberadaan planet/sistem keplanetan di bintang -bintang lain. Metode-metode tersebut antara lain:<br /></div><ol style="font-weight: bold; color: rgb(0, 153, 0);"><li>Kecepatan radial (pergeseran Doppler)<br /></li><li>Astrometri (proper motion, sangat terbatas)<br /></li><li>Gravitasi Mikrolensa (planet dan bintang induk berada di depan bintang latar belakang)<br /></li><li>Metode Transit (planet lewat di depan bintang induk)<br /></li><li>Piringan Circumbintang (distorsi awan debu oleh planet yang mengorbit)<br /></li><li>Pengamatan Direct (langsung) oleh teropong Spitzer.</li></ol><div style="text-align: justify;"><div style="text-align: justify;"><span style="font-weight: bold; color: rgb(51, 0, 153);"><br />1. METODE PERGESERAN DOPPLER</span> <span style="font-weight: bold; color: rgb(51, 51, 153);">(KECEPATAN RADIAL/KR)</span><br /><br />Jika astrometri langsung mengamati bintang, maka metode KR, mengamati gerak bintang dari spektrum cahaya. Yakni secara sistematik memperhatikan pergeseran garis spektrum serapan dan pancaran. Dengan teleskop sekarang, hanya dapat diukur kecepatan sedikitnya 3 m/s. Bumi, misalnya hanya mempengaruhi gerak matahari sebesar 0.1 m/s. Dengan mengukur T dan mendapatkan massa bintang, m<span style="font-weight: bold;font-size:85%;" ><sub>BINTANG</sub></span>, bisa ditemukan 1/2 sumbu panjang orbit.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbAveEhGwkAnJZTa1tSROK19Xj-SCbQokqP4-G5RP9kgSEsLnrto6m0kLN97I_m3dGFATXAHz1eRkFALPQZDuLbE17S0i0muFTEx7OYD5sHV5t14ZLBVLbBGkOz2iUHDo2OQg-QLBW44zB/s1600/slide0005_image021.gif"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 138px; height: 52px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbAveEhGwkAnJZTa1tSROK19Xj-SCbQokqP4-G5RP9kgSEsLnrto6m0kLN97I_m3dGFATXAHz1eRkFALPQZDuLbE17S0i0muFTEx7OYD5sHV5t14ZLBVLbBGkOz2iUHDo2OQg-QLBW44zB/s400/slide0005_image021.gif" alt="" id="BLOGGER_PHOTO_ID_5569792288705433474" border="0" /></a><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6RXFm35vPLwQTqKrGZjfhXZMjyMwQmMsYesrXzppo4uOwtumnpsPmq0QeUJRdR6D0jXTw0XWoDpX420SoLx7O1OcTlRtZUg4V4uqx6c0f-ePo7yRvQR0sOGhDzS7VxhhZQ489cBHwpJwz/s1600/slide0005_image018.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 300px; height: 221px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6RXFm35vPLwQTqKrGZjfhXZMjyMwQmMsYesrXzppo4uOwtumnpsPmq0QeUJRdR6D0jXTw0XWoDpX420SoLx7O1OcTlRtZUg4V4uqx6c0f-ePo7yRvQR0sOGhDzS7VxhhZQ489cBHwpJwz/s400/slide0005_image018.png" alt="" id="BLOGGER_PHOTO_ID_5569792289594412418" border="0" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1QdpsxX7P995mgD09EkrFfspHy5d-JCRRHk_ad74nyAObJuEHE948lBagyxYUO5LpjVlE3d87BY9gr_Wabs92ij8nbnXSGDXwahzt5yQYUx8QP75JZW0ZPMUYc2oBcLfPPNGwzQ7q2oCt/s1600/Picture3.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 254px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1QdpsxX7P995mgD09EkrFfspHy5d-JCRRHk_ad74nyAObJuEHE948lBagyxYUO5LpjVlE3d87BY9gr_Wabs92ij8nbnXSGDXwahzt5yQYUx8QP75JZW0ZPMUYc2oBcLfPPNGwzQ7q2oCt/s400/Picture3.png" alt="" id="BLOGGER_PHOTO_ID_5569793116062259346" border="0" /></a><br />Jika massa bintang dapat diturunkan dari (mis. Diagram H-R) dan inklinasi orbit terhadap bidang ekliptika, i, diketahui, maka massa planet, m<sub style="font-style: italic;">P</sub> dapat dihitung dengan persamaan di bawah ini. Jika i tidak dapat diketahui, maka yang kita peroleh hanyalah m<sub style="font-style: italic;">P</sub> sin i. <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDbQOO0btUfuc8I7d16P8FK83he2Kx3Z4AdTst0EwrUK3UY3MvIRnnTUEoLT5o-SmYCFvK7_TZTvsnMm4gDVgaeZZOTeQ2LVDGNWB_INTTqZNd3aqdp-QJb0Pvh0ou7XQV4iNkMAmCkQ7d/s1600/slide0007_image029.gif"><img style="float: right; margin: 0pt 0pt 10px 10px; cursor: pointer; width: 149px; height: 59px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDbQOO0btUfuc8I7d16P8FK83he2Kx3Z4AdTst0EwrUK3UY3MvIRnnTUEoLT5o-SmYCFvK7_TZTvsnMm4gDVgaeZZOTeQ2LVDGNWB_INTTqZNd3aqdp-QJb0Pvh0ou7XQV4iNkMAmCkQ7d/s320/slide0007_image029.gif" alt="" id="BLOGGER_PHOTO_ID_5569794715036567874" border="0" /></a><br /><br /><br /><br /><br />Jadi sekarang kita sudah dapat menghitung massa planet (bila mengetahui inklinasi atau dengan mengambil asumsi).<br /><br /><div style="text-align: justify;">Kecepatan radial untuk beberapa planet:<br />u/ Jupiter: v = 13 m/detik dan periode T = 12 tahun.<br />u/ Bumi : v = 0.09 m/detik dan periode T = 1 tahun<br />Limit deteksi hanya 3 m/detik, jadi planet-planet semacam Bumi sangat sulit teramati.<br /><br />Penemuan pertama extrasolar planet terjadi di tahun 1995 di bintang 51 Pegasus.<br />Kini, lebih dari 120 planet seukuran Yupiter telah ditemukan di bintang-bintang lain dengan metode KR/Doppler. Orbit-orbitnya pendek, eksentrisitas tinggi serta harga massa mencapai setinggi 10 massa Yupiter.<br /><span style="font-weight: bold; color: rgb(51, 0, 153);"><br />2. METODE ASTROMETRI</span><span style="font-weight: bold; color: rgb(51, 51, 153);"></span><br /></div><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfVwOrwt4ihosKn7jJngLN9j6HUNCuY23Ft6Hed62qoslKm-Mc15iwcDXc1EOj81FBtHHfM-3DWq9jSfm40GUXWUwij1YeN6CMTOpHjlLuhSbNd6uRB02sfkWQ6hMpdqWTlqnBr_O29bU6/s1600/Picture4.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 272px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfVwOrwt4ihosKn7jJngLN9j6HUNCuY23Ft6Hed62qoslKm-Mc15iwcDXc1EOj81FBtHHfM-3DWq9jSfm40GUXWUwij1YeN6CMTOpHjlLuhSbNd6uRB02sfkWQ6hMpdqWTlqnBr_O29bU6/s400/Picture4.png" alt="" id="BLOGGER_PHOTO_ID_5569795885877595474" border="0" /></a><br />Pertanyaannya: Dapatkah keberadaan planet seperti Jupiter diketahui dengan astrometri?<br /><br />Sayang sekali, belum dapat. Mengapa? Mari kita lakukan perhitungan singkat.<br /><br />Matahari mengorbit pusat gravitasi Matahari-Yupiter pada jejari orbit hanya 1.2 jejari matahari. 1.2 jejari matahari memetakan sudut sebesar 5.2 x 10<sup>-3</sup> detikbusur pada jarak 1 parsec – atau 5.2 x 10<sup>-4</sup> detikbusur pada jarak 10 pc. Kecermatan pengukuran hingga sudut sekecil itu masih belum dapat (sulit) dilakukan.<br /><br /><span style="font-weight: bold; color: rgb(51, 0, 153);">3. METODE MIKROLENSA</span> (memanfaatkan sifat/fenomena gravitational lensing)<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE9fC3d9uuI4hxRYqIjTJZNlGFi7TPteuyY3C7o5w2WhlAdKlwMJuL2szxbyYrbqd7mbuX-2e11qM34KMqwNmcwxh8juIdO-TOX-nPv5d0S0romwqKSIkUfKYhDVgwpV6QF2O8B0DJqvAw/s1600/slide0024_image045.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 240px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE9fC3d9uuI4hxRYqIjTJZNlGFi7TPteuyY3C7o5w2WhlAdKlwMJuL2szxbyYrbqd7mbuX-2e11qM34KMqwNmcwxh8juIdO-TOX-nPv5d0S0romwqKSIkUfKYhDVgwpV6QF2O8B0DJqvAw/s400/slide0024_image045.png" alt="" id="BLOGGER_PHOTO_ID_5569797027534395586" border="0" /></a><br />Gravitasi Mikrolensa terjadi jika planet dan bintang induk berada di depan bintang latar belakang.<br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0VWDNSFms7TI5APFxOJZdxj8D93gwd8Vm_fqUHku2IyRhZOtCuVbXFiZzBurXjwbnSidfJ4KydaWvPJvX7xAi5VEwcW04dkhvN0uaLntVn_f5qkWlUGAVPlAh9FG51kGlQ4IUo1uN_Q3G/s1600/slide0023_image047.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 345px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0VWDNSFms7TI5APFxOJZdxj8D93gwd8Vm_fqUHku2IyRhZOtCuVbXFiZzBurXjwbnSidfJ4KydaWvPJvX7xAi5VEwcW04dkhvN0uaLntVn_f5qkWlUGAVPlAh9FG51kGlQ4IUo1uN_Q3G/s400/slide0023_image047.png" alt="" id="BLOGGER_PHOTO_ID_5569797710962499282" border="0" /></a><span style="font-weight: bold; color: rgb(51, 0, 153);"><br />4. METODE TRANSIT</span><br /><br />Saat sebuah planet (benda gelap) melintas di depan bintang induknya, sebagian sinar bintang induknya akan terhalangi (ter-gerhana-i) oleh planet yang melintas. Peristiwa ini disebut <span style="color: rgb(255, 0, 0);">t</span><span style="font-weight: bold; color: rgb(255, 0, 0);">ransit planet</span> (lihat diagram di bawah ini). Astronom akan mencari bintang2 yang kecerlangannya menurun secara periodik.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizDbmqm7zAYUsVmlFfSTQJsgW5wN8xbMobUyhdbecEn6WFIG_0onPsheezQC7YmTKtcOVslyKUt4juiOLMn60gr8v1N_EZ3w__iso41oDPomONurDJsKK-AWR5BPdcoJMshxJJcu3j82Hs/s1600/slide0009_image055.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 250px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizDbmqm7zAYUsVmlFfSTQJsgW5wN8xbMobUyhdbecEn6WFIG_0onPsheezQC7YmTKtcOVslyKUt4juiOLMn60gr8v1N_EZ3w__iso41oDPomONurDJsKK-AWR5BPdcoJMshxJJcu3j82Hs/s400/slide0009_image055.png" alt="" id="BLOGGER_PHOTO_ID_5569799673384179058" border="0" /></a><br />Jika sebuah bintang jauh di transit oleh sebuah planet semacam Yupiter, terjadi penurunan flux sinar sebesar 1% di bintang itu dari semulanya.<br /><br />Sebuah planet yang telah ditemukan di bintang HD209458 dengan metode KR; pada tahun 1999, diamati kembali flux bintangnya. Ditemukan transit tepat pada waktu yang telah diramal sebelumnya. Seperti planet di 51Peg, planet itu besar dan mengorbit dekat sekali dengan bintang – planet semacam ini dikenali sebagai “hot Jupiters”.<br /><br />Metode transit inilah yang digunakan oleh <span style="font-weight: bold; color: rgb(255, 0, 0);">Teleskop Keppler.</span> Teleskop ini dikhususkan untuk 'mencari' planet serupa Bumi. (penjelasan lebih detailnya silakan lihat di <a href="http://en.wikipedia.org/wiki/Kepler_%28spacecraft%29">sini </a>dan <a href="http://kepler.nasa.gov/">sini</a>). Hasil kerja teleskop ini dapat dibaca pada link yang diberikan.<br /><br /><a href="http://upload.wikimedia.org/wikipedia/commons/3/3f/Keplerpacecraft.019e.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 341px;" src="http://upload.wikimedia.org/wikipedia/commons/3/3f/Keplerpacecraft.019e.jpg" alt="" border="0" /></a><br /><span style="font-weight: bold; color: rgb(51, 0, 153);">5. METODE PENGAMATAN LANGSUNG DENGAN TEROPONG SPITZER</span><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEik60XVnM38GuanyWA36Zpn0zCEbx0YxPo4Axdr6xvLYvl0m_TS4evlmnHqIwPPVjjEqE5vHVQbKCVX4knC2ukk8q1hXfS49q6DkYJWuRpLiHJDExPvNW207zBuiKYQbHVakaRuxcxNNKJc/s1600/slide0026_image060.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEik60XVnM38GuanyWA36Zpn0zCEbx0YxPo4Axdr6xvLYvl0m_TS4evlmnHqIwPPVjjEqE5vHVQbKCVX4knC2ukk8q1hXfS49q6DkYJWuRpLiHJDExPvNW207zBuiKYQbHVakaRuxcxNNKJc/s400/slide0026_image060.png" alt="" id="BLOGGER_PHOTO_ID_5569801109727155762" border="0" /></a><br /><span style="font-weight: bold; color: rgb(0, 0, 153);">KESIMPULAN</span><br /><ul><li> Metode KR hanya dapat mendeteksi planet-planet masif (sedikitnya 1/5 massa Yupiter) dengan periode relatif yang sangat pendek.</li><li> Kebanyakan planet-planet yang terdeteksi berada sangat dekat dengan bintang (kurang dari ~0.1SA)</li><li> 3-4% bintang-bintang serupa matahari memiliki planet-planet jenis itu</li><li> Sejumlah kecil planet-planet yang lebih jauh umumnya mempunyai orbit yang lebih eksentrik (e >~0.2)</li></ul>Planet-planet yang sudah ditemukan beserta informasi massa bintang induk dan periode orbitnya.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPOel9-aoQEfLT2BLVZ1M87LF5mNFBFe8olF-omjbuDXxoT0bWTRm3zkmorAyccynLbE28BffC1aviOMRtIWj-js86fBHQtSh8X4ZULLKjZRcYG9VuKiAVCVOHVe0TLiWb1jZhaSX-G20P/s1600/slide0021_image067.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 343px; height: 535px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPOel9-aoQEfLT2BLVZ1M87LF5mNFBFe8olF-omjbuDXxoT0bWTRm3zkmorAyccynLbE28BffC1aviOMRtIWj-js86fBHQtSh8X4ZULLKjZRcYG9VuKiAVCVOHVe0TLiWb1jZhaSX-G20P/s400/slide0021_image067.png" alt="" id="BLOGGER_PHOTO_ID_5569803002979166402" border="0" /></a><br />Bintang - bintang di angkasa ini sangat banyak. Bagaimana astronom dapat memilih bintang mana yang diamati/dicurigai memiliki sistem planet?<br /><br />Sistem planet tidak bisa terbentuk pada bintang bintang yang luminositasnya besar. Hal ini disebabkan bintang-bintang seperti ini memiliki massa hidup yang cenderung singkat. Bintang-bintang generasi I (yang terbentuk dari material Big Bang) juga tidak mungkin memiliki sistem keplanetan karena kurangnya unsur-unsur berat. Jadi, bintang-bintang yang mungkin memiliki sistem keplanetan adalah bintang-bintang yang tidak terlalu panas dan termasuk Generasi ke dua atau lebih (bintang yang materialnya berasal dari sisa material bintang lain yang meledak lewat Supernova/hembusan saat pembentukan Planetary Nebulae).<br /><br /><span style="font-weight: bold; color: rgb(255, 102, 0);">LATIHAN</span><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjduYz68xGaUklv5x4egddDPZIz70ptJHbuw6JHNcwmDyv8jojh7Bqgm7ktyhysgM3FYB3IlCWe7ZfuemB9CyscsUDAZECpRSpB1J_Iun2A8RDfW0I7CkXfX-mjWds9Au1xOEBLGtiNpk0R/s1600/slide0020_image066.gif"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 288px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjduYz68xGaUklv5x4egddDPZIz70ptJHbuw6JHNcwmDyv8jojh7Bqgm7ktyhysgM3FYB3IlCWe7ZfuemB9CyscsUDAZECpRSpB1J_Iun2A8RDfW0I7CkXfX-mjWds9Au1xOEBLGtiNpk0R/s400/slide0020_image066.gif" alt="" id="BLOGGER_PHOTO_ID_5569803421823673250" border="0" /></a><br /><span style="font-weight: bold; color: rgb(255, 102, 0);">Sumber:</span><br />1. Materi pelatihan olimpiade Astronomi oleh Tim Astronomi ITB<br />2. Wikipedia<br /><br />notes: jika ingin melihat gambar yang ada dengan lebih jelas, silakan klik di masing-masing gambar<br /><br /><span style="font-weight: bold; color: rgb(255, 0, 0);">SELAMAT BELAJAR</span><br /></div></div>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-7835130099283684649.post-263107267927332792011-01-31T16:40:00.004+07:002011-01-31T16:45:57.265+07:00A Sense Of Planetary Scale<p></p><div style="text-align: center;"><iframe src="http://player.vimeo.com/video/19231255" frameborder="0" height="225" width="400"></iframe></div><p><br /></p><div style="text-align: justify;">Blogger Brad Goodspeed created an animation which shows different planets in our solar system as they would appear in the sky if it shared an orbit with our Moon, 380,000 km from earth. On his blog, he said he created it “to make you feel small.”<br /></div><p><br />Source: <a href="http://vimeo.com/19231255">Brad Goodspeed</a></p>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-75620498773507848372011-01-27T10:42:00.007+07:002011-01-27T11:06:24.845+07:00Hubble Discovers Most Distant Galaxy Yet!<div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbSeSiPYvsTvSW0aoNPkBFSy5b_qam3jVjb5SqoyBquqRzolcTzu_jORzqrTgX6GDXjlY2tfB2hGNH11ZXuJYfw3xsIiavN9ntiwqOSwX4_Rn0b6NMlHKlYjN5VuVhyphenhyphenL430yKQ7hKzx1U8/s1600/600px-Hubble_Ultra_Deep_Field_part_d.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbSeSiPYvsTvSW0aoNPkBFSy5b_qam3jVjb5SqoyBquqRzolcTzu_jORzqrTgX6GDXjlY2tfB2hGNH11ZXuJYfw3xsIiavN9ntiwqOSwX4_Rn0b6NMlHKlYjN5VuVhyphenhyphenL430yKQ7hKzx1U8/s400/600px-Hubble_Ultra_Deep_Field_part_d.jpg" alt="" id="BLOGGER_PHOTO_ID_5566707796141549714" border="0" /></a><span style="font-size:78%;"><span style="font-style: italic; color: rgb(255, 0, 0); font-weight: bold;font-size:85%;" >Hubble Ultra Deep Field - Part D</span><br /></span></div><br /><div style="text-align: justify;">No Princess is sending holographic help messages. No Hans Solo is warming up a Millenium Falcon to jump into hyperdrive. We don’t even have a Death Star waiting around the corner. But, what we do have is evidence that astronomers have pushed the Hubble Space Telescope to its limits and have seen further back in time than ever before. “<span style="font-weight: bold; color: rgb(0, 102, 0);">We are looking back through 96% of the life of the universe, and in so doing, we have found just one galaxy, but it is one, but it is a remarkable object</span>. <span style="font-weight: bold; color: rgb(0, 0, 153);">The universe was only 500 million years old at that time versus it now being thirteen thousand-seven hundred million years old</span>. ” said Garth Illingworth, Ames Research Scientist. We know about the Hubble Ultra Deep Field, but we invite you to boldy go on…</div><p style="text-align: justify;">While studying ultra-deep imaging data from the Hubble Space Telescope, an international group of astronomers have found what may be the most distant galaxy ever seen, about 13.2 billion light-years away. “Two years ago, a powerful new camera was put on Hubble, a camera which works in the infrared which we had never really good capability before, and we have now taken the deepest image of the universe ever using this camera in the infrared.” said Garth Illingworth, professor of astronomy and astrophysics at the University of California, Santa Cruz. “We’re getting back very close to the first galaxies, which we think formed around 200 to 300 million years after the Big Bang.” The study pushed the limits of Hubble’s capabilities, extending its reach back to about 480 million years after the Big Bang, when the universe was just 4 percent of its current age. The dim object, called UDFj-39546284, is a compact galaxy of blue stars that existed 480 million years after the Big Bang, only four percent of the universe’s current age. It is tiny. Over one hundred such mini-galaxies would be needed to make up our Milky Way.</p><p style="text-align: justify;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyHkAICQqnCK2fH1oq9UVg6SVcXvWlgk7662NrqaMQyYS6b7AbOA4_OS6UUL_JYldlo3uZu4a3GSHNCnx-nOfGhxyE-mFa-VgGoQFOCi1XZ-KElYgTVjX6tKjzKb9Qt6JNm2JhmUTW5bRW/s1600/512542main_old-object-670.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyHkAICQqnCK2fH1oq9UVg6SVcXvWlgk7662NrqaMQyYS6b7AbOA4_OS6UUL_JYldlo3uZu4a3GSHNCnx-nOfGhxyE-mFa-VgGoQFOCi1XZ-KElYgTVjX6tKjzKb9Qt6JNm2JhmUTW5bRW/s400/512542main_old-object-670.jpg" alt="" id="BLOGGER_PHOTO_ID_5566707802830992370" border="0" /></a></p><p style="text-align: center; color: rgb(204, 0, 0); font-style: italic; font-weight: bold;"><span style="font-size:85%;">The farthest and one of the very earliest galaxies ever seen in the universe appears as a faint red blob in this ultra-deep–field exposure taken with NASA's Hubble Space Telescope. This is the deepest infrared image taken of the universe. Based on the object's color, astronomers believe it is 13.2 billion light-years away. (Credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), R. Bouwens (University of California, Santa Cruz, and Leiden University), and the HUDF09 Team)</span></p><p style="text-align: justify;">Illingworth and UCSC astronomer Rychard Bouwens (now at Leiden University in the Netherlands) led the study, which will be published in the January 27 issue of Nature. U<span style="font-weight: bold; color: rgb(0, 102, 0);">sing infrared data gathered by Hubble’s Wide Field Planetary Camera 3 (WFC3), they were able to see dramatic changes in galaxies over a period from about 480 to 650 million years after the Big Bang. The rate of star birth in the universe increased by ten times during this 170-million-year period</span>, Illingworth said. “This is an astonishing increase in such a short period, just 1 percent of the current age of the universe,” he said. There were also striking changes in the numbers of galaxies detected. “<span style="font-weight: bold; color: rgb(102, 0, 204);">Our previous searches had found 47 galaxies at somewhat later times when the universe was about 650 million years old. However, we could only find one galaxy candidate just 170 million years earlier</span>,” Illingworth said. “The universe was changing very quickly in a short amount of time.”</p><p style="text-align: justify;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkPNDwD_jgA26MW39YKsF2CKJ3D7PGqHOJhYlvRQdMlBIMHUFuKGZJDHWa5lvr56_lHWuZNx4kaGMiOf0GX_gYN_DWZmkgdox3IwFNFGXSsN1m-CchyEUREiU4W-A4hudoRsRYfxouzWGp/s1600/nicpar1ir.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkPNDwD_jgA26MW39YKsF2CKJ3D7PGqHOJhYlvRQdMlBIMHUFuKGZJDHWa5lvr56_lHWuZNx4kaGMiOf0GX_gYN_DWZmkgdox3IwFNFGXSsN1m-CchyEUREiU4W-A4hudoRsRYfxouzWGp/s400/nicpar1ir.jpg" alt="" id="BLOGGER_PHOTO_ID_5566707805562201554" border="0" /></a></p><p style="text-align: center; font-style: italic; color: rgb(255, 0, 0); font-weight: bold;"><span style="font-size:85%;">The Hubble Ultra Deep Field WFC3/IR Image. This Region of the Sky Contains the Deepest Optical and Near-Infrared Images Ever Taken of the Universe and is useful for finding star-forming galaxies at redshifts 8 and 10 (650 and 500 million years after the Big Bang, respectively). At UCSC and Leiden, we are using these data to better understand the properties of the first galaxies. Credit: Bouwen</span></p><p style="text-align: justify;">According to Bouwens, these findings are consistent with the hierarchical picture of galaxy formation, in which galaxies grew and merged under the gravitational influence of dark matter. “We see a very rapid build-up of galaxies around this time,” he said. “For the first time now, we can make realistic statements about how the galaxy population changed during this period and provide meaningful constraints for models of galaxy formation.” <span style="color: rgb(255, 0, 0);">Astronomers gauge the distance of an object from its redshift, a measure of how much the expansion of space has stretched the light from an object to longer (“redder”) wavelengths</span>. <span style="font-weight: bold; color: rgb(0, 0, 153);">The newly detected galaxy has a likely redshift value (“z”) of 10.3, which corresponds to an object that emitted the light we now see 13.2 billion years ago, just 480 million years after the birth of the universe</span>. “This result is on the edge of our capabilities, but we spent months doing tests to confirm it, so we now feel pretty confident,” Illingworth said.</p><p style="text-align: justify;">The galaxy, a faint smudge of starlight in the Hubble images, is tiny compared to the massive galaxies seen in the local universe. Our own Milky Way, for example, is more than 100 times larger. The researchers also described three other galaxies with redshifts greater than 8.3. The study involved a thorough search of data collected from deep imaging of the Hubble Ultra Deep Field (HUDF), a small patch of sky about one-tenth the size of the Moon. During two four-day stretches in summer 2009 and summer 2010, Hubble focused on one tiny spot in the HUDF for a total exposure of 87 hours with the WFC3 infrared camera.</p><p style="text-align: justify;"><object style="height: 253px; width: 415px;"><param name="movie" value="http://www.youtube.com/v/oAVjF_7ensg?version=3"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/oAVjF_7ensg?version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="253" width="415"></embed></object></p><p style="text-align: justify;">“NASA continues to reach for new heights, and this latest Hubble discovery will deepen our understanding of the universe and benefit generations to come,” said NASA Administrator Charles Bolden, who was the pilot of the space shuttle mission that carried Hubble to orbit. “We could only dream when we launched Hubble more than 20 years ago that it would have the ability to make these types of groundbreaking discoveries and rewrite textbooks.”</p><p style="text-align: justify;">To go beyond redshift 10, astronomers will have to wait for Hubble’s successor, the James Webb Space Telescope (JWST), which NASA plans to launch later this decade. JWST will also be able to perform the spectroscopic measurements needed to confirm the reported galaxy at redshift 10. “It’s going to take JWST to do more work at higher redshifts. This study at least tells us that there are objects around at redshift 10 and that the first galaxies must have formed earlier than that,” Illingworth said.</p><p style="text-align: justify;">“After 20 years of opening our eyes to the universe around us, Hubble continues to awe and surprise astronomers,” said Jon Morse, NASA’s Astrophysics Division director at the agency’s headquarters in Washington. “It now offers a tantalizing look at the very edge of the known universe — a frontier NASA strives to explore.” How far back will we go? If you sit around a campfire watching the embers climb skywards and discuss cosmology after an observing night with your astro friends, someone will ultimately bring up the topic of space/time curvature. If you put an X on a balloon and expand it – and trace round its expanse – you will eventually return to your mark. If we see our beginnings, will we also eventually see our end coming up over the horizon? Wow… Pass the marshmallows, please. We’ve got a lot to think about.</p><p style="text-align: justify;"><i><b>Reader Info</b>: Illingworth’s team maintains the <a href="http://firstgalaxies.org/" target="blank">First Galaxies</a> website, with information about the latest research on distant galaxies. In addition to Bouwens and Illingworth, the coauthors of the Nature paper include Ivo Labbe of Carnegie Observatories; Pascal Oesch of UCSC and the Institute for Astronomy in Zurich; Michele Trenti of the University of Colorado; Marcella Carollo of the Institute for Astronomy; Pieter van Dokkum of Yale University; Marijn Franx of Leiden University; Massimo Stiavelli and Larry Bradley of the Space Telescope Science Institute; and Valentino Gonzalez and Daniel Magee of UC Santa Cruz. This research was supported by NASA and the Swiss National Science Foundation. Hubble Ultra Deep Field Image and Video courtesy of NASA/STSci.</i></p>Source: <a href="http://www.universetoday.com/82855/long-ago-in-a-galaxy-far-far-away/">Universe Today</a><br /><br /><span style="font-weight: bold; color: rgb(255, 0, 0);font-size:130%;" >Short Quiz: </span><br /><span style="color: rgb(0, 0, 153);">Can you calculate the velocity of that distant galaxy (</span><span style="color: rgb(0, 0, 153);">UDFj-39546284</span><span style="color: rgb(0, 0, 153);">) moving away from us? and, why is the more distant galaxy is younger than the closer one?</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-69033268326389346902010-12-08T13:13:00.004+07:002010-12-08T13:22:37.774+07:00Tipe - Tipe Galaksi<div style="text-align: justify;">Dengan mempergunakan teleskop 250 cm di Observatorium Mount Palomar, astronom <span style="font-weight: bold; color: rgb(255, 102, 0);"></span><span style="font-weight: bold; color: rgb(255, 102, 0);">Edwin Hubble (1924) </span>memotret sebuah galaksi di rasi Andromeda. Dia menjelaskan, untuk ertama kalinya, bentuk galaksi yang kemudian terkenal dengan nama galaksi Andromeda, berjarak 2 juta tahun cahaya dari galaksi kita (Bimasakti/Milkyway). Galaksi Andromeda merupakan galaksi luar (extra galaxy) pertama yang diketahui astronom. Sejak penemuannya, banyak studi dilakukan dalam mempelajari galaksi-galaksi di luar galaksi Bimasakti tempat kita berada.<br /></div><div style="text-align: justify;"><br />Upaya para astronom mempelajari galaksi melalui pengamatan semenjak abad ke-18, telah melahirkan berbagai katalog benda-benda langit yang meliputi gugusan bintang termasuk didalamnya adalah galaksi. Pada tahun 1888, J.L.E. Dreyer mempublikasikan New General Catalogue of nebulae and Clusters of Stars yang memuat 7840 obyek langit. Katalog ini dilengkapi dengan suplemennya, Index Catalogues pada tahun 1895 dan 1908. Umumnya katalog tersebut mempergunakan notasi NGC atau IC diikuti dengan nomor obyek dalam daftar. Sebagai contoh, galaksi Andro-meda diberi nomor katalogus NGC 224.<br /><br />Ada banyak galaksi-galaksi dengan berbagai ragam bentuknya. <span style="font-weight: bold; color: rgb(51, 51, 153);">Hubble mengklasifikasikan galaksi-galaksi berdasarkan bentuknya ke dalam 3 kelompok utama</span>, yakni:<br /><br /><span style="font-weight: bold; color: rgb(255, 0, 0);">1. Galaksi spiral (S)</span><br />Populasi galaksi berbentuk spiral ini yang terbanyak (80%). Galaksi ini memiliki struktur yang paling teratur dengan pusat, selubung bulat dan piringan dengan lengan spiral yang mengelilingi ekuator galaksi. Variasi dari galaksi spiral adalah galaksi spiral berbatang (SB), dengan bentuk cerutu yang melintasi pusat dan di kedua ujungnya pola spiral menjuntai.<br /><br /><span style="font-weight: bold; color: rgb(0, 0, 153);">2. Galaksi eliptik (E)</span><br />Galaksi dengan bentuk ini meliputi 17% dari seluruh populasi galaksi di alam semesta. Bentuknya lebih sederhana dibandingkan dengan galaksi spiral, karena hanya terdiri dari pusat dan selubung pipih. Kerapatan bintang lebih tinggi di pusat dibanding di tepiannya.<br /><br /><span style="font-weight: bold; color: rgb(0, 153, 0);">3. Galaksi tidak beraturan</span><br />Sebanyak 3% dari galaksi yang teramati sejauh ini menunjukkan bentuk yang tidak beraturan. Bentuknya lebih merupakan onggokan bintang dengan batas yang kurang jelas. Berbagai contoh nyata galaksi ini antara lain Awan Magellan kecil dan besar, tetangga galaksi kita, Bima Sakti.<br />Pola galaksi yang dirangkum dan diklasifikasikan oleh Hubble ditafsirkannya sebagai perjalanan evolusi galaksi di alam semesta dari bentuk yang awalnya sangat teratur menuju bentuk yang tidak beraturan.<br /></div><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuQR4AnQmlmj5bCQATZlO9te_uL6zL1coWjn1t3njKiBPutguh8e749RPRSGhYKpVlygLR4SwsxlAf7mI3iHBu47BXrxGRAnPZ5KSjBB6Hwpw5n9GEcsEfWTQ3yyQqrm6mJLf4oA0DhXmt/s1600/fork+diagram+-+Hubble.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 283px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuQR4AnQmlmj5bCQATZlO9te_uL6zL1coWjn1t3njKiBPutguh8e749RPRSGhYKpVlygLR4SwsxlAf7mI3iHBu47BXrxGRAnPZ5KSjBB6Hwpw5n9GEcsEfWTQ3yyQqrm6mJLf4oA0DhXmt/s400/fork+diagram+-+Hubble.png" alt="" id="BLOGGER_PHOTO_ID_5548191856921941842" border="0" /></a>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-48834315052626180952010-11-21T06:07:00.003+07:002010-11-21T06:12:58.230+07:00Soal - soal Latihan<span style="font-family:trebuchet ms;">1. Bulan memerlukan waktu paling tidak 2 menit untuk terbit dilihat dari Bumi. Berapa lama Bumi memerlukan waktu untuk terbit dilihat oleh seorang pengamat dari Bulan? </span><br /><span style="font-family:trebuchet ms;">a. 2 menit </span><br /><span style="font-family:trebuchet ms;">b. 4 menit </span><br /><span style="font-family:trebuchet ms;">c. 6 menit </span><br /><span style="font-family:trebuchet ms;">d. 8 menit </span><br /><span style="font-family:trebuchet ms;">e. Bumi tidak terbit dan tidak tenggelam </span><br /><br /><span style="font-family:trebuchet ms;">2. On the sunlit side of the Moon the sky appears … </span><br /><span style="font-family:trebuchet ms;">A. white because of the extreme brilliance of the sunlight </span><br /><span style="font-family:trebuchet ms;">B. black because the Earth blocks the light </span><br /><span style="font-family:trebuchet ms;">C. blue due to the Moons' atmosphere </span><br /><span style="font-family:trebuchet ms;">D. black because the Moon lacks an atmosphere </span><br /><span style="font-family:trebuchet ms;">E. black because the Moon has a dense atmosphere</span><br /><br /><span style="font-family:trebuchet ms;">3. You are adrift at sea, and you see a star directly overhead. You remember from your astronomy lab at N.C. State that this star has a declination of 42 degrees South, and a Right Ascension of 8 hours. From this information alone, you know that … </span><br /><span style="font-family:trebuchet ms;">A) You are adrift at a point north latitude 42 degrees. </span><br /><span style="font-family:trebuchet ms;">B) You are adrift at a point south latitude 42 degrees. </span><br /><span style="font-family:trebuchet ms;">C) You are adrift at a point west longitude 8 degrees. </span><br /><span style="font-family:trebuchet ms;">D) You are adrift at a point south latitude 48 degrees. </span><br /><span style="font-family:trebuchet ms;">E) A and C</span><br /><br /><span style="font-family:trebuchet ms;">4. If you lived on the Moon, would the motion of the planets appear any different than from Earth? </span><br /><span style="font-family:trebuchet ms;">A. The motion of the planets would not appear significantly different than on the Earth. </span><br /><span style="font-family:trebuchet ms;">B. The planets would not appear to go around the Moon. </span><br /><span style="font-family:trebuchet ms;">C. The planets would not appear to go around the Earth. </span><br /><span style="font-family:trebuchet ms;">D. The planets would not appear to go around the Sun. </span><br /><span style="font-family:trebuchet ms;">E. None of the above </span><br /><br /><span style="font-family:trebuchet ms;">5. You are carried away by an alien spacecraft to a different star planetary system. You are set down on a planet with cloudless skies. After some time, you notice five planets in the sky. Three retrograde after greatest eastern elongation with the "sun"; two at opposition. From this observation, you infer that, in a heliocentric model, you are on the _____ planet outward from the "sun". </span><br /><span style="font-family:trebuchet ms;">A. first </span><br /><span style="font-family:trebuchet ms;">B. second </span><br /><span style="font-family:trebuchet ms;">C. third </span><br /><span style="font-family:trebuchet ms;">D. fourth </span><br /><span style="font-family:trebuchet ms;">E. fifth </span><br /><br /><span style="font-family:trebuchet ms;">6. When Venus sets after sunset … </span><br /><span style="font-family:trebuchet ms;">a. Venus is west of the sun </span><br /><span style="font-family:trebuchet ms;">b. Venus is east of the sun </span><br /><span style="font-family:trebuchet ms;">c. Venus could be either east or west of the sun depending on the month. </span><br /><span style="font-family:trebuchet ms;">d. it is a mistake because Venus never sets after sunset </span><br /><span style="font-family:trebuchet ms;">e. it must be moving retrograde </span><br /><br /><span style="font-family:trebuchet ms;">7. Pernyataan tentang gerak planet yang tepat adalah ... </span><br /><span style="font-family:trebuchet ms;">A. Planet Venus mungkin saja terlihat saat tengah malam </span><br /><span style="font-family:trebuchet ms;">B. Planet Jupiter tidak mungkin tertutup oleh bulan Purnama </span><br /><span style="font-family:trebuchet ms;">C. Planet Mars selalu nampak berdekatan dengan Matahari </span><br /><span style="font-family:trebuchet ms;">D. Planet Merkurius tidak mungkin nampak melintas di depan piringan Matahari </span><br /><span style="font-family:trebuchet ms;">E. Planet Saturnus bisa mengalami gerak retrogade </span><br /><br /><span style="font-family:trebuchet ms;">8. Peristiwa yang tidak tepat berhubungan dengan pengamat yang ada tepat di kutub utara adalah ... </span><br /><span style="font-family:trebuchet ms;">A. Matahari paling tinggi ada di 23,50 di atas horizon </span><br /><span style="font-family:trebuchet ms;">B. Pada bulan Desember, Matahari tidak terbit </span><br /><span style="font-family:trebuchet ms;">C. Semua arah adalah arah selatan </span><br /><span style="font-family:trebuchet ms;">D. Bisa mengamati rasi Centaurus di bulan-bulan tertentu </span><br /><span style="font-family:trebuchet ms;">E. Bintang Polaris menjadi bintang sirkumpolar </span><br /><br /><span style="font-weight: bold;">Selamat Belajar</span>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-7835130099283684649.post-14112053162595403392010-11-08T21:52:00.006+07:002010-11-08T22:02:46.392+07:00Solar SystemA couple videos related to the solar system:<br /><br /><center><object height="321" width="400"><param name="movie" value="http://www.youtube.com/v/16zeA-c-3vw?fs=1&hl=en_US"><param name="allowFullScreen" value="true"><param name="allowscriptaccess" value="always"><embed src="http://www.youtube.com/v/16zeA-c-3vw?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="321" width="400"></embed></object><br /><br /><object height="321" width="400"><param name="movie" value="http://www.youtube.com/v/B1AXbpYndGc?fs=1&hl=en_US"><param name="allowFullScreen" value="true"><param name="allowscriptaccess" value="always"><embed src="http://www.youtube.com/v/B1AXbpYndGc?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="321" width="400"></embed></object><br /><br /><object height="241" width="400"><param name="movie" value="http://www.youtube.com/v/iBqjob-UVeo?fs=1&hl=en_US"><param name="allowFullScreen" value="true"><param name="allowscriptaccess" value="always"><embed src="http://www.youtube.com/v/iBqjob-UVeo?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="241" width="400"></embed></object></center><br /><span style="font-weight: bold;">Source: youtube</span><br /><br /><span style="font-weight: bold;"></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-70692070257765249982010-11-02T14:04:00.001+07:002010-12-08T13:24:44.167+07:00Latihan Soal: Gerak Benda Langit1. Tentukan perbandingan gaya pasang surut antara Bumi-Bulan dan Bumi-Matahari bila diketahui jarak pusat ke pusat antara Bumi-Matahari 400 kali jarak pusat ke pusat Bumi-Bulan, diameter Bumi 4 kali diameter Bulan, dan massa Bumi 80 kali massa Bulan!<br /><br />2. Sebuah satelit mempunyai orbit polar dengan ketinggian 5,49 x 10^6 m di atas permukaan Bumi. Setelah melewati di atas London, tentukan posisi satelit saat menyelesaikan satu kali orbit!<br /><br />3. Mengapa objek langit yang besar (misalkan Matahari, Bintang, Planet, dll) bentuknya mendekati bola sedangkan objek langit yang relatif kecil (misalkan Asteroid, Komet, dll) bentuknya irregular?<br /><br />4. Certain neutron stars are believed to be rotating at about 1 revolution/second. If such a star has a radius of 20 km, what must be its minimum mass so that material on its surface remains in place during the rapid rotation?<br /><br />5. Planet imajiner mempunyai jarak rata-rata 120 satuan astronomi dari matahari. Berapa lama waktu yang diperlukan planet ini untuk mengorbit matahari? Berapa periode sinodisnya?<br /><br /><br />Selamat Belajar.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-28585651643313706752010-09-24T20:29:00.004+07:002010-09-24T20:37:59.170+07:00Introducing Lomba Rancang Pabrik Tingkat NasionalMemperkenalkan website <a href="http://lrptn.com/">www.lrptn.com</a> sebagai sumber informasi bagi acara Lomba rancang Pabrik Tingkat Nasional.<br /><div style="display: none;" class="gsc-config gsc-blogConfig"><form class="gsc-config gsc-blogConfig"></form></div><div class="gsc-resultsRoot gsc-tabData gsc-tabdInactive"><table class="gsc-resultsHeader" cellpadding="0" cellspacing="0"><tbody><tr><td class="gsc-twiddleRegionCell"><div class="gsc-twiddle"><div class="gsc-title"><br /></div></div><div class="gsc-results-selector gsc-more-results-active"><div title="tampilkan satu hasil" class="gsc-result-selector gsc-one-result"> </div><div title="tampilkan lebih banyak hasil" class="gsc-result-selector gsc-more-results"> </div><div title="tampilkan semua hasil" class="gsc-result-selector gsc-all-results"> </div></div></td><td class="gsc-configLabelCell"><br /></td></tr></tbody></table></div><div class="post-header"> </div> <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://lrptn.com/"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 400px; height: 253px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6JaFgHpJkeEC1m7BYgipHcPQQzRMgoND_iQy62xmqtcLYJBc6AHUml1ugNYBItp-dnEPJ5rXzYxaJESqxVUHQyeRJhOfT2j-IgL_h2delPI0XeaSIM5z5rAH-qZdmVNSl8ZKk97zxmZQ/s400/Untitled.jpg" alt="" id="BLOGGER_PHOTO_ID_5519641647314145970" border="0" /></a><br /><span style="color: rgb(0, 0, 153);font-size:130%;" ><span style="font-weight: bold;">Sekilas mengenai LRPTN (Source: <a href="http://lrptn.com/">www.lrptn.com</a>)</span></span><br /><br /><div style="text-align: justify;">Perkembangan industri kimia saat ini tidak lepas dari kemampuan dan kreativitas para insinyurnya, yang selalu memberikan ide-ide baru sehingga dapat memenuhi kebutuhan masyarakat. Kecakapan seorang insinyur tentunya tidak diperoleh secara instan, namun perlu dibentuk semenjak duduk di bangku kuliah. Untuk meningkatkan kemampuan dan kreativitas para calon insinyur teknik kimia, Himpunan Mahasiswa Teknik Kimia (HIMATEK) ITB bekerjasama dengan Program Studi Teknik Kimia ITB mengadakan Lomba Rancang Pabrik Tingkat Nasional (LRPTN). LRPTN merupakan sebuah kompetisi rancang pabrik yang mengangkat tema-tema yang berkaitan dengan isu-isu aktual dalam dunia industri. Sampai sekarang, LRPTN telah berhasil diselenggarakan sebanyak 11 kali sejak tahun 1996. </div><p style="text-align: justify;">LRPTN yang pertama kali diadakan diikuti oleh 8 kelompok peserta dari berbagai perguruan tinggi di Indonesia dengan dewan juri terpillih, yang memiliki kompetensi dalam menilai rancangan suatu pabrik dari sudut pandang keilmuan, khususnya Teknik Kimia. Rangkaian acara LRPTN diisi oleh pembicara-pembicara yang secara khusus diundang untuk berbagi pengetahuan dan pengalaman menarik mereka berkaitan dengan tema dari tiap LRPTN. Semenjak LRPTN IV pada tahun 2000, kompetisi ini dikategorikan menjadi 2, yaitu kategori perancangan pabrik dan problem solving. Kategori perancangan pabrik ini dilombakan dengan pembatasan berdasarkan subtema utama dari LRPTN, sedangkan untuk kategori problem solving dilombakan untuk memfasilitasi ide-ide solutif dan inovatif dari mahasiswa dalam memecahkan masalah nyata yang sedang terjadi dalam suatu pabrik tertentu.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Selanjutnya, pada LRPTN V yang diselenggarakan pada tahun 2001, kategori LRPTN diubah menjadi 3 kategori, yaitu Lomba Rancang Pabrik Kategori A, Lomba Rancang Pabrik Kategori B, dan problem solving. “ Format kompetisi LRPTN dengan 3 kategori tersebut dianggap mampu memfasilitasi ide-ide solutif dan inovatif dari mahasiswa sehingga penyelenggaraan LRPTN berikutnya, mulai dari LRPTN VII hingga LRPTN XI mengikuti format yang hampir sama dengan LRPTN V. Banyak pihak memandang LRPTN merupakan suatu kegiatan yang memberi dampak positif bagi perkembangan mahasiswa Teknik Kimia di Indonesia dalam meningkatkan kemampuan aplikatif mahasiswa dalam melakukan suatu pra rancangan pabrik. Hal ini ditunjukkan dengan peningkatan jumlah peserta yang turut bergabung untuk mengikuti LRPTN ini tiap tahunnya.</p><div style="text-align: justify;"> </div><p style="text-align: center;"><a href="http://www.lrptn.com/wp-content/uploads/2010/09/29877_1392045194565_1035203819_31169281_2701281_n.jpg"><img style="width: 389px; height: 292px;" class="aligncenter size-full wp-image-228" title="pemenang LRPTN XI april 2010" src="http://www.lrptn.com/wp-content/uploads/2010/09/29877_1392045194565_1035203819_31169281_2701281_n.jpg" alt="" /></a></p><div style="text-align: justify;"> </div><p style="text-align: justify;">Penyelenggaraan LRPTN diharapkan dapat menjadi suatu wadah berkarya bagi mahasiswa se-Indonesia dalam lingkup keilmuan Teknik Kimia. Selain itu, LRPTN ini juga diharapkan dapat memberikan kontribusi nyata bagi perkembangan industri nasional.</p>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-68795518003028582522010-05-07T00:46:00.005+07:002010-05-07T00:51:07.947+07:00Hubble 20 years of Space-Shattering DiscoveriesA nice video from NASA to celebrate 20 years of Hubble Telescope.<br /><br /><center><object height="248" width="400"><param name="movie" value="http://www.youtube.com/v/--X9zfgZtS0&hl=en_US&fs=1&hd=1&border=1"><param name="allowFullScreen" value="true"><param name="allowscriptaccess" value="always"><embed src="http://www.youtube.com/v/--X9zfgZtS0&hl=en_US&fs=1&hd=1&border=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="248" width="400"></embed></object></center><br /><br />Source: <a href="http://www.youtube.com/watch?v=--X9zfgZtS0">youtube.com</a>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-34590685749621096192010-05-07T00:41:00.002+07:002010-05-07T00:44:36.284+07:00Soal Latihan Astronomi Dasar<div style="text-align: justify;">Silakan mencoba beberapa latihan soal Astronomi.<br /><br />1. If you measure the parallax of a star to be 0,5 arc seconds on Earth and an observer in a space station in the orbit around the Sun measures a parallax for the same star to be 1 arc seconds, how far is the space station from the Sun ?<br /><br />2. Sebuah galaksi yang berada pada jarak d Mpc dari kita. Tunjukkan bahwa pada galaksi ini, bentangan 1” di langit berkorespondensi dengan bentangan fisik 5d parsec!<br /><br />3. Para ahli menggunakan sinar laser untuk menentukan jarak dari Bumi ke planet Venus. Sinar laser ditembakkan ke arah planet Venus , lalu para ahli mengukur selang waktu antara penembakkan sinar laser dengan pantulan yang diterima oleh detektor tertentu. Jika didapat selang waktunya adalah 4,32178 menit. Hitunglah jarak planet Venus dari Bumi !<br /><br />4. Teleskop di Bumi mempunyai kemampuan memisahkan objek (resolving power) sebesar 0”,1. Berapakah ukuran kawah minimum yang dapat diamati di permukaan Mars ?<br /><br />5. You observe an asteroid approaching the Earth. You have two observatories 3200 km apart, so you can measure the parallax shift of the incoming asteroid. You observe the parallax shift to be 0,022 degrees.<br />a) How big is the parallax shift in radians ?<br />b) How far away is the asteroid ?<br /><br />Selamat belajar.<br /></div>Unknownnoreply@blogger.com5tag:blogger.com,1999:blog-7835130099283684649.post-46552712462122992952010-03-14T06:47:00.004+07:002010-03-14T06:59:58.920+07:00Sekilas Tentang Badai Matahari<div style="text-align: justify;">Matahari adalah sumber dari semua energi yang kita kenal di Bumi. Jika kita merunut semua sumber energi yang kita kenal dan kita gunakan sehari-hari, semuanya akan bermuara pada Matahari. Matahari sendiri menghasilkan energi lewat reaksi nuklir yang terjadi di pusatnya. Namun, meski Matahari memegang peran penting sebagai sumber energi yang kita butuhkan, Matahari juga menyimpan potensi yang bisa memberikan ancaman bagi manusia dan ekosistem Bumi. Ancaman yang dimaksud adalah peristiwa yang dikenal dengan nama badai matahari.<br /></div><div style="text-align: justify;"><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8qeD8sf9J1KoU7TZmLrO7b1yN0g7z8UG2IeM75bHm2jAIs4hS_QxBdt87nNtYL-pvZSyyxCKIS8VE6iFHdIEoWEYs3CUNEl8tgLBzko81zdmmzXawcMeejD2MhbVsquYeVE2-VAVN4Ess/s1600-h/strukturmthr.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 316px; height: 305px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8qeD8sf9J1KoU7TZmLrO7b1yN0g7z8UG2IeM75bHm2jAIs4hS_QxBdt87nNtYL-pvZSyyxCKIS8VE6iFHdIEoWEYs3CUNEl8tgLBzko81zdmmzXawcMeejD2MhbVsquYeVE2-VAVN4Ess/s400/strukturmthr.jpg" alt="" id="BLOGGER_PHOTO_ID_5448270132022028450" border="0" /></a><span style="font-size:85%;"><span style="font-weight: bold;">Gambar 1. Struktur Matahari</span></span><br /><br /></div>Sebelum membicarakan tentang badai matahari, kita akan melihat sekilas tentang Matahari. Matahari adalah sebuah bintang, yaitu bola plasma panas yang ditopang oleh gaya gravitasi. Di pusat Matahari (nomor 1 dalam Gambar 1), terjadi reaksi nuklir (fusi) yang mengubah 4 atom hidrogen menjadi 1 atom helium. Reaksi fusi tersebut, selain menghasilkan helium, juga menghasilkan energi dalam jumlah melimpah (ingat persamaan terkenal oleh Einstein: E=mc<sup>2</sup>). Energi yang dihasilkan, di pancarkan keluar melewati bagian-bagian Matahari, yaitu: zona radiatif (nomor 2), zona konventif (nomor 3), dan bagian atmosfer Matahari, yang terdiri dari fotosfer (nomor 4), kromosfer (nomor 5), dan korona (nomor 6). Dan badai Matahari adalah peristiwa yang berkaitan dengan bagian atmosfer Matahari tersebut.</div><div style="text-align: justify;"> </div><p style="text-align: justify;">Bagian terluar dari Matahari, yaitu korona, memiliki temperatur yang mencapai jutaan kelvin. <span style="font-weight: bold; color: rgb(255, 0, 0);">Dengan temparatur yang tinggi tersebut, materi yang berada di korona Matahari memiliki energi kinetik yang besar</span>. <span style="font-weight: bold; color: rgb(255, 0, 0);">Tarikan gravitasi Matahari tidak cukup kuat untuk mempertahankan materi korona yang memiliki energi kinetik yang besar itu dan secara terus menerus, partikel bermuatan yang berasal dari korona, akan lepas keluar angkasa</span>. Aliran partikel ini dikenal dengan nama angin matahari, yang terutama terdiri dari elektron dan proton dengan energi sekitar 1 keV. Setiap tahunnya, sebanyak 10<sup>12</sup> ton materi korona lepas menjadi angin matahari, yang bergerak dengan kecepatan antara 200-700 km/s.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Berbeda dengan pusat Matahari yang relatif sederhana, bagian atmosfer Matahari relatif lebih rumit. Karena di atmosfer Matahari ini, medan magnetik Matahari berperan besar terhadap berbagai peristiwa yang terjadi di dalamnya. Ada berbagai fenomena menarik diamati di atmosfer Matahari berkaitan dengan medan magnetik Matahari, seperti bintik matahari (<em>sun spot</em>), ledakan Matahari (<em>solar flare</em>), prominensa, dan pelontaran material korona (CME – <em>Coronal Mass Ejection</em>). Hal-hal inilah yang berkaitan dengan badai matahari.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Jadi apa yang dimaksud dengan badai matahari?</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Singkatnya, badai matahari adalah kejadian/event dimana aktivitas Matahari berinteraksi dengan medan magnetik Bumi. Badai matahari ini berkaitan langsung dengan peristiwa <em>solar flare</em> dan CME. Kedua hal itulah yang menyebabkan terjadinya badai matahari.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Solar flare adalah ledakan di Matahari akibat terbukanya salah satu kumparan medan magnet permukaan Matahari. Ledakan ini melepaskan partikel berenergi tinggi dan radiasi elektromagnetik pada panjang gelombang sinar-x dan sinar gamma. Partikel berenergi tinggi yang dilepaskan oleh peristiwa <em>solar flare</em>, jika mengarah ke Bumi, akan mencapai Bumi dalam waktu 1-2 hari. Sedangkan radiasi elektromagnetik energi tingginya, akan mencapai Bumi dalam waktu hanya sekitar 8 menit.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Lalu bagaimana dengan CME?</p><div style="text-align: justify;"> </div><p style="text-align: justify;">CME adalah pelepasan material dari korona yang teramati sebagai letupan yang menyembur dari permukaan Matahari. Dalam semburan material korona ini, sekitar 2×10<sup>11</sup> – 4×10<sup>13</sup> kilogram material dilontarkan dengan energi sebesar 10<sup>22</sup> – 6×10<sup>24</sup> joule. Material ini dilontarkan dengan kecepatan mulai dari 20 km/s sampai 2000 km/s, dengan rata-rata kecepatan 350 km/s. Untuk mencapai Bumi, dibutuhkan waktu 1-3 hari.</p><div style="text-align: justify;"> </div><p style="text-align: justify;"><span style="font-weight: bold; color: rgb(255, 0, 0);">Matahari kita memiliki siklus keaktifan dengan periode sekitar 11 tahun</span>. <span style="font-weight: bold; color: rgb(0, 153, 0);">Siklus keaktifan ini berkaitan dengan pembalikan kutub magnetik di permukaan Matahar</span>i. <span style="font-weight: bold; color: rgb(0, 153, 0);">Keaktifan Matahari ini bisa dilihat dari jumlah bintik matahari yang teramat</span>i. <span style="font-weight: bold; color: rgb(255, 102, 0);">Saat keaktifan Matahari mencapai maksimum, kita akan mengamati bintik matahari dalam jumlah paling banyak di permukaan Matahari</span> dan pada saat keaktifan Matahari mencapai maksimum inilah, angin matahari lebih ‘kencang’ dari biasanya dan partikel-partikel yang dipancarkan juga lebih energetik. Dan peristiwa <em>solar flare</em> dan CME dalam skala besar juga lebih dimungkinkan untuk terjadi. Dengan kata lain, saat keaktifan Matahari mencapai maksimum, Bumi akan lebih banyak dipapar dengan partikel-partikel bermuatan tinggi (lebih tinggi dari biasanya) dan radiasi elektromagnetik energi tinggi.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Partikel-partikel bermuatan yang dipancarkan dari peristiwa<em> solar flare</em> dan CME, saat mencapai Bumi, akan berinteraksi dengan medan magnetik Bumi. Interaksi ini akan menyebabkan gangguan pada medan magnetik Bumi buat sementara.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Saat partikel-partikel bermuatan dengan energi tinggi mencapai Bumi, ia akan diarahkan oleh medan magnetik Bumi, untuk bergerak sesuai dengan garis-garis medan magnetik Bumi, menuju ke arah kutub utara dan kutub selatan magnetik Bumi. Saat partikel-partikel energetik tersebut berbenturan dengan partikel udara dalam atmosfer Bumi, ia akan menyebabkan partikel udara (terutama nitrogen) terionisasi. Bagi kita yang berada di permukaan Bumi, yang kita amati adalah bentuk seperti tirai-tirai cahaya warna-warni di langit, yang dikenal dengan nama aurora. <span style="font-weight: bold; color: rgb(255, 102, 0);">Aurora ini bisa diamati dari posisi lintang tinggi di sekitar kutub magnetik Bumi (utara dan selatan)</span>.</p><p style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5RR_tf6LBo-98NAHMgagY8RUuSxTySdaqq84ObMmA6JlWLAx-d7wNZHG49vO_5ANftVmxfODanHANpwZiqgFcXHMzeGylUVu7SWGN1Kp76Bu_2c39S7juuJUak1o5pNslGSKu0weYgFjr/s1600-h/aurora.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 400px; height: 241px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5RR_tf6LBo-98NAHMgagY8RUuSxTySdaqq84ObMmA6JlWLAx-d7wNZHG49vO_5ANftVmxfODanHANpwZiqgFcXHMzeGylUVu7SWGN1Kp76Bu_2c39S7juuJUak1o5pNslGSKu0weYgFjr/s400/aurora.jpg" alt="" id="BLOGGER_PHOTO_ID_5448270137692581698" border="0" /></a></p><p style="text-align: center;"><span style="font-size:85%;"><span style="font-weight: bold;">Gambar 2. Aurora</span></span></p><p style="text-align: justify;">Saat terjadi badai matahari, partikel-partikel energetik tadi tidak hanya menghasilkan aurora yang indah yang bisa di amati di lintang tinggi. Tapi bisa memberikan dampak yang relatif lebih besar dan lebih berbahaya. Dampak yang dimaksud antara lain: gangguan pada jaringan listrik karena transformator dalam jaringan listrik akan mengalami kelebihan muatan, gangguan telekomunikasi (merusak satelit, menyebabkan <em>black-out</em> frekuensi HF radio, dll), navigasi, dan menyebabkan korosi pada jaringan pipa bawah tanah.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Peristiwa gangguan besar yang disebabkan oleh badai matahari, yang paling terkenal adalah peristiwa tahun 1859, peristiwa yang dikenal dengan nama Carrington Event. Saat itu, jaringan komunikasi telegraf masih relatif baru tapi sudah luas digunakan. Ketika terjadi badai Matahari tahun 1859, jaringan telegraf seluruh Amerika dan Eropa mati total. Aurora yang biasanya hanya bisa diamati di lintang tinggi, saat itu bahkan bisa diamati sampai di equator.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Masih ada beberapa contoh peristiwa lain yang berkaitan dengan badai matahari yang terjadi dalam abad ke-20 dan 21:</p><div style="text-align: justify;"> </div><ol style="text-align: justify;"><li> 13 maret 1989: Terjadi CME besar 4 hari sebelumnya. Badai geomagnetik menghasilkan arus listrik induksi eksesif hingga ribuan ampere pada sistem interkoneksi kelistrikan Ontario Hydro (Canada). Arus induksi eksesif ini menyebabkan sejumlah trafo terbakar. Akibat dari terbakarnya trafo tsb, jaringan listrik di seluruh Quebec (Canada) putus selama 9 jam. Guncangan magnetik badai sekitar seperempat Carrington event, (sekitar 400 nT). Aurora teramati sampai di Texas</li><li>Januari 1994 : 2 buah satelit komunikasi Anik milik Canada rusak akibat digempur elektron-elektron energetik dari Matahari. Satu satelit bisa segera pulih dalam waktu beberapa jam, namun satelit lainnya baru bisa dipulihkan 6 bulan kemudian.<br />Total kerugian akibat lumpuhnya satelit ini disebut mencapai US $ 50 – 70 juta.</li><li>November 2003 : Mengganggu kinerja instrumen WAAS berbasis GPS milik FAA AS selama 30 jam.</li><li>Januari 2005: Berpotensi mengakibatkan <em>black-out</em> di frekuensi HF radio pesawat, sehingga penerbangan United Airlines 26 terpaksa dialihkan menghindari rute polar (kutub) yang biasa dilaluinya.</li></ol><div style="text-align: justify;"> </div><p style="text-align: justify;">Badai Matahari juga bisa berbahaya bagi makhluk hidup secara biologi. Bahaya ini terutama bagi para astronot yang kebetulan sedang berada di luar angkasa saat badai matahari terjadi. Bagi kita yang berada di permukaan Bumi, kita relatif aman terlindungi oleh medan magnetik Bumi. Pengaruh langsung dari badai matahari ini hanya dialami oleh binatang-binatang yang peka terhadap medan magnetik Bumi. Karena badai matahari mengganggu medan magnetik Bumi, maka binatang-binatang yang peka terhadap medan magnetik akan secara langsung terimbas. Misalnya burung-burung, lumba-lumba, dan paus, yang menggunakan medan magnetik Bumi untuk menentukan arah, untuk sesaat ketika badai matahari terjadi, mereka akan kehilangan arah.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Saat ini, Matahari sedang menuju puncak keaktifan dalam siklusnya yang ke-24. Puncak keaktifan Matahari ini diperkirakan terjadi sekitar tahun 2011-2013. Saat puncak keaktifan Matahari pada siklus ke-24 ini, diperkirakan tidak akan jauh berbeda dengan saat puncak keaktifan pada siklus-siklus sebelumnya. Mungkin efeknya akan sedikit lebih besar, tapi ada juga yang menduga akan terjadi hal yang sebaliknya, justru lebih kecil efeknya. Yang manapun itu kasusnya, bisa dikatakan semua ahli fisika matahari sepakat tidak mungkin terjadi peristiwa besar yang akan membahayakan kehidupan di muka Bumi.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Berdasarkan pengetahuan kita saat ini, badai matahari hanya akan memberikan ancaman bahaya yang rendah. <em>Solar flare</em> dan CME yang terjadi di Matahari, tidak akan cukup untuk menyebabkan peristiwa seperti yang digambarkan dalam beberapa film yang beredar belakangan ini. Beberapa bintang yang diamati memang menunjukkan adanya peristiwa yang dikenal dengan istilah superflare, yaitu flare seperti yang kita amati di Matahari tapi dengan intensitas yang jauh lebih besar. Tapi peristiwa serupa diduga bukan peristiwa yang umum dan diragukan bakal terjadi pada Matahari kita, setidaknya saat ini. Memang peristiwa<em> solar flare</em> dan CME belum bisa diprediksi dengan baik untuk saat ini. Tapi pengetahuan kita yang didapat dari pengamatan Matahari lewat berbagai observatorium landas-bumi dan wahana antariksa yang terus menerus mengamati Matahari, kita semakin mengerti berbagai peristiwa yang terjadi di Matahari. <span style="font-weight: bold; color: rgb(255, 0, 0);">Setidaknya untuk saat ini, kita bisa mengatakan dengan cukup yakin bahwa yang digambarkan dalam film-film fiksi ilmiah (misalnya: film <span style="color: rgb(255, 0, 0);">2012</span>) tentang badai raksasa matahari, tidak akan terjadi dalam waktu dekat</span>.</p><p style="text-align: justify;">Seiring dengan perkembangan teknologi elektronika, serta kaitannya dengan iklim, studi tentang aktivitas matahari menjadi perhatian yang semakin perlu dikaji. Bisakah kita memprediksi badai matahari? Dinamika siklusnya? Dinamika cuaca antariksa yang di dorong dinamika matahari? Pengamatan matahari saat ini telah menggunakan teknologi satelit dalam menentukan bilamanakah terjadi aktivitas yang tiba-tiba dari matahari.<span id="more-41"></span></p> <p style="text-align: justify;">SOHO (Solar Heliospheric Observatory), diluncurkan untuk terus menerus memonitor matahari; ACE (Advance Composition Explorer), mengamati perubahan lingkungan antariksa dan memberikan peringatan adanya badai matahari, satu jam sebelum mencapai bumi. WIND yang mengawasi angin matahari yang terjadi pada ruang antar planet sekitar bumi, atau IMAGE (Imager for Magnetopause-to-Auroral Global Exploration) mengamati partikel bermuatan dan atom netral disekitar magnetosfer. Kesemuanya itu digunakan untuk memahami fenomena yang terjadi pada matahari dan keterkaitannya dengan lingkungan bumi. Tetapi pemahaman yang lebih baik lagi akan diperoleh jika kita bisa memahami bagaimana dinamika yang sesungguhnya terjadi jauh di dalam matahari, dan mendorong terjadinya dinamika yang teramati. Dan dengan dukungan pengamatan yang semakin baik, kajian yang semakin mendalam mendorong semakin berkembangnya studi bidang astronomi, khusunya astrofisika bintang/matahari. (Gambar dari SOHO ditampilkan pula di dalam blog ini, di bagian kanan)</p><span style="font-weight: bold;">Sumber: <span style="color: rgb(51, 51, 255);">www.langitselatan.com</span></span>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-7835130099283684649.post-74876169521766162362010-03-02T07:32:00.002+07:002010-03-02T07:44:03.679+07:00Soal - soal latihan astronomi 2Silakan mencoba kedua soal di bawah ini. Soal-soal ini merupakan soal olimpiade astronomi siswa di India.<br /><br /> <p class="MsoListParagraphCxSpFirst" style="margin: 0in 0in 0.0001pt 0.25in; text-align: justify; text-indent: -0.25in; line-height: normal;"><!--[if !supportLists]--><span style="font-size: 12pt; font-family: "Times New Roman","serif";"><span style="">1.<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span><!--[endif]--><span style="font-size: 12pt; font-family: "Times New Roman","serif";">Jayshree claimed that she saw a solar eclipse when the size of the solar disk was 26</span><span style="font-size: 12pt; font-family: "Times New Roman","serif";">’ </span><span style="font-size: 12pt; font-family: "Times New Roman","serif";">and that of the lunar disk was 30</span><span style="font-size: 12pt; font-family: "Times New Roman","serif";">′</span><span style="font-size: 12pt; font-family: "Times New Roman","serif";">. She also claimed that at the time of the maximum eclipse, distance between the centres of the two disks was 7</span><span style="font-size: 12pt; font-family: "Times New Roman","serif";">′</span><span style="font-size: 12pt; font-family: "Times New Roman","serif";">. Qualitatively show that she could not have observed a total eclipse. Find the percentage of the solar disk covered at the time of the maximum eclipse.<o:p></o:p></span></p> <p class="MsoListParagraphCxSpMiddle" style="margin: 0in 0in 0.0001pt 0.25in; text-align: justify; line-height: normal;"><span style="font-size: 12pt; font-family: "Times New Roman","serif";"><o:p> </o:p></span></p> <p class="MsoListParagraphCxSpLast" style="margin: 0in 0in 0.0001pt 0.25in; text-align: justify; text-indent: -0.25in; line-height: normal;"><!--[if !supportLists]--><span style="font-size: 12pt; font-family: "Times New Roman","serif";"><span style="">2.<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span><!--[endif]--><span style="font-size: 12pt; font-family: "Times New Roman","serif";">A year in Solar calendar consist of 365.25 days and the same in Lunar calendar consist of 354 days. The additional days in Solar calendar are kept as balance every year. Whenever the number of balance days exceeds 30, an additional month of 30 days is added to the lunar year to offset the difference. The cycle goes on. Anwesh, whose birthday falls on 1st January, noticed that in the year 2008, his birthday coincided with the start of the lunar year. In which earliest future year, his birthday will again coincide with the start of the lunar year?<o:p></o:p></span></p> <br />Solusinya dapat di download di <a href="http://www.4shared.com/file/232492834/fdd8b0d2/solusi.html">sini</a>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-63464135246251800532010-02-09T12:39:00.003+07:002010-02-09T12:50:15.954+07:00Where did today’s spiral galaxies come from?<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQ3hyphenhyphenrldZfCBe1wEklSrIOa12-6RIkMTy5xkdJHBUN34xlfGat7CV9b8jVwVqY3YchVocit5I8JnSdmIOCryK6_ARF9MlrRZ6bvYxusd8z_d_X6RyZkjhshslTAhX3B91wl4g0soVQUi_v/s1600-h/heic1002a_H1.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 357px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQ3hyphenhyphenrldZfCBe1wEklSrIOa12-6RIkMTy5xkdJHBUN34xlfGat7CV9b8jVwVqY3YchVocit5I8JnSdmIOCryK6_ARF9MlrRZ6bvYxusd8z_d_X6RyZkjhshslTAhX3B91wl4g0soVQUi_v/s400/heic1002a_H1.jpg" alt="" id="BLOGGER_PHOTO_ID_5436114813220277154" border="0" /></a><br /><div style="text-align: justify;">Hubble shows that the beautiful spirals galaxies of the modern Universe were the ugly ducklings of six billion years ago.<br /><br /><a name="subhead1"></a><span style="font-weight: bold; color: rgb(255, 0, 0);">If confirmed, the finding highlights the importance to many galaxies of collisions and mergers in the recent past. It also provides clues for the unique status of our own galaxy, the Milky Way. </span>Using data from the NASA/ESA Hubble Space Telescope, astronomers have created a census of galaxy types and shapes from a time before Earth and the Sun existed, up to the present day. <span style="font-weight: bold; color: rgb(255, 0, 0);">The results show that, contrary to contemporary thought, more than half of the present-day spiral galaxies had peculiar shapes as recently as 6 billion years ago.</span><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaowXtaSYePsWSJCpevTg7gybrEChR249MkJq32SkZYuP0oMOZzTjlaD4ySNyKh8ve30SxaKG3O45UHJMdhazDAy_BiYRLCnxkAs9kcTk40O1yguAAzNX7YRsO_HGtSwPRkLi6foBTHllw/s1600-h/heic0602a_HI.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 400px; height: 313px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaowXtaSYePsWSJCpevTg7gybrEChR249MkJq32SkZYuP0oMOZzTjlaD4ySNyKh8ve30SxaKG3O45UHJMdhazDAy_BiYRLCnxkAs9kcTk40O1yguAAzNX7YRsO_HGtSwPRkLi6foBTHllw/s400/heic0602a_HI.jpg" alt="" id="BLOGGER_PHOTO_ID_5436116422608518850" border="0" /></a><br />The study of the shapes and formation of galaxies, known as morphology, is a critical and much-debated topic in astronomy. An important tool for this is the ‘<span style="font-weight: bold; color: rgb(0, 102, 0);">Hubble sequence’ or the ‘Hubble tuning-fork diagram’,</span> a classification scheme invented in 1926 by the same Edwin Hubble in whose honour the space telescope is named. </div><p style="text-align: justify; color: rgb(0, 0, 153);"> <span style="font-weight: bold;">Hubble’s scheme divides regular galaxies into three broad classes — ellipticals, lenticulars and spirals — based on their visual appearance. A fourth class contains galaxies with an irregular appearance. </span></p><div style="text-align: justify;">A team of European astronomers led by François Hammer of the Observatoire de Paris has, for the first time, completed a census of galaxy types at two different points in the Universe’s history — in effect, creating two Hubble sequences — that help explain how galaxies form. In this survey, researchers sampled 116 local galaxies and 148 distant galaxies.<br /><br />The astronomers show that the Hubble sequence six billion years ago was very different from the one that astronomers see today. “<span style="font-weight: bold; color: rgb(255, 0, 0);">Six billion years ago, there were many more peculiar galaxies than now – a very surprising result</span>,” says Rodney Delgado-Serrano, lead author of the related paper recently published in Astronomy & Astrophysics. “This means that in the last six billion years, these peculiar galaxies must have become normal spirals, giving us a more dramatic picture of the recent Universe than we had before.” The astronomers think that <span style="font-weight: bold; color: rgb(0, 153, 0);">these peculiar galaxies did indeed become spirals through collisions and merging. Although it was commonly believed that galaxy mergers decreased significantly eight billion years ago, the new result implies that mergers were still occurring frequently after that time</span> <span style="color: rgb(51, 204, 0); font-weight: bold;"><span style="color: rgb(0, 153, 0);">— up to as recently as four billion years ago</span>.</span> “Our aim was to find a scenario that would connect the current picture of the Universe with the morphologies of distant, older galaxies — to find the right fit for this puzzling view of galaxy evolution,” says Hammer.<br /><br />Also contrary to the widely held opinion that galaxy mergers result in the formation of elliptical galaxies, Hammer and his team support a scenario in which these cosmic clashes result in spiral galaxies. In a parallel paper published in <i>Astronomy & Astrophysics</i>, they delve further into their ‘spiral rebuilding’ hypothesis, which proposes that <span style="font-weight: bold; color: rgb(255, 0, 0);">peculiar galaxies affected by gas-rich mergers are slowly reborn as giant spirals with discs and central bulges</span>. Although our own Galaxy is a spiral galaxy, it seems to have been spared much of the drama; its formation history has been rather quiet and it has avoided violent collisions in astronomically recent times. However, the large Andromeda Galaxy from our neighbourhood has not been so lucky and fits well into the ‘spiral rebuilding’ scenario. Researchers continue to seek explanations for this.<br /><br /><b>Notes for editors:</b><br /><br />The Hubble Space Telescope is a project of international cooperation between ESA and NASA. </div><p style="text-align: justify;"> Hammer and his team used data from the Sloan Digital Sky Survey undertaken by Apache Point Observatory, New Mexico, USA, and from the GOODS field and Hubble Ultra Deep Field taken by the Advanced Camera for Surveys aboard Hubble. </p><p style="text-align: justify;"> R. Delgado-Serrano, et al., 2010, <a href="http://arxiv.org/abs/0906.2805">How was the Hubble Sequence 6 Giga-years ago?</a> <i>Astronomy & Astrophysics</i>, 509, A78. </p><div style="text-align: justify;"> F. Hammer et al., 2009, <a href="http://arxiv.org/abs/0903.3962">The Hubble Sequence: just a vestige of merger events?</a> <i>Astronomy & Astrophysics</i>, 507, 1313.<br /><br />Source: <a href="http://www.esa.int/esaSC/SEMW6HVJ15G_index_0.html">ESA</a><br /></div>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-7835130099283684649.post-25977256997595548372010-02-06T18:35:00.003+07:002010-02-06T18:40:25.806+07:00Close Up Pictures Of Pluto's Face<div style="text-align: justify;">Since discovered in 1930, there has never been observed which can provide a detailed picture of the face of Pluto. Although Pluto is an interesting object, even a topic of debate will be the definition of Pluto in 2006; but Pluto is still difficult to observe and record the details, because a small and distant. </div><p style="text-align: justify;">However, <em>Hubble Space Telescope</em> (HST), has changed all that. With the observations that have been conducted since 1994, until the recent images taken between the years 2002-2003, then obtained a more detailed picture of Pluto, rather than observations that have been made ever. These results are a long way from the details, because the challenge to record details such as a soccer ball from a distance of 60 km.<br /></p><p style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHGeRggl-cw2X0y4MhuF6t0MKn0ixr7rhMlMIzaQTBBUk0BOWSkFR6o3M7TbS_awPmA_xTlSjxF8tXTl4EnnPzzTWJkjnwT0j9MgDzjE_gPpsJqkcO_9-q0JC18RGKjeOWxJkvQ8CgmQU1/s1600-h/leadpluto2010.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 400px; height: 162px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHGeRggl-cw2X0y4MhuF6t0MKn0ixr7rhMlMIzaQTBBUk0BOWSkFR6o3M7TbS_awPmA_xTlSjxF8tXTl4EnnPzzTWJkjnwT0j9MgDzjE_gPpsJqkcO_9-q0JC18RGKjeOWxJkvQ8CgmQU1/s400/leadpluto2010.jpg" alt="" id="BLOGGER_PHOTO_ID_5435093656709047394" border="0" /></a></p><div style="text-align: center;"><span style="font-size:85%;">Change the face of Pluto Hubble Space Telescope is seen. Credit: Hubble</span></div><p style="text-align: justify;">Although the image of the HST is not enough to be able to record details of craters and mountains, and even then if there is one, but the recording is done the world HST indicates that vary in color, from white, dark orange-brown to dark. The colors are believed due to ultra-violet radiation from the sun which is in the distance, breaking the existing methane on Pluto's surface, causing a dark brown residue rich in carbon. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Pluto is also changing illumination, in the northern polar region of southern luminous and dark and reddish. The summer approaching Pluto's north pole causes ice to melt and experiencing freezing in the darker areas due terbayangi on the planet. HST has shown that Pluto is not just a ball of ice and rock, but a world that has a dramatic change in atmosphere. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Change season due to the elliptical orbit of Pluto 248 years along with the slanted axis. Season becomes elliptical symmetry because Pluto's orbit. Spring transition into summer in the polar hemisphere rapidly occurred in the north, because Pluto is moving very fast along the orbit as it moves around the Sun in the direction of approach. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Earth Observation landing between 1988 and 2002 showed the mass multiplication of the atmosphere have all the time allegedly due to heating and sublimation of nitrogen ice. HST images of the season to give an understanding of what happened on Pluto and the fate of the atmosphere. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">HST image of this is that terdetil at the moment, at least until the <em>New Horizon</em> spacecraft will fly past Pluto and will record more detailed images again, and give a better picture of what is happening on the surface of Pluto, and was still waiting until 2015 to will come. </p><div style="text-align: justify;">Source: Hubblesite and <a href="http://langitselatan.com/2010/02/05/close-up-wajah-pluto/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+langitselatan+%28langitselatan.com%29">Langit Selata</a><a href="http://langitselatan.com/2010/02/05/close-up-wajah-pluto/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+langitselatan+%28langitselatan.com%29">n</a><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-17297581370449627872010-01-26T23:33:00.006+07:002010-01-27T00:07:11.030+07:00Soal-Soal Latihan Astronomi 2010Silakan didownload beberapa file soal-soal latihan yang dapat digunakan sebagai bahan diskusi dan latihan. Selamat belajar dan semoga bermanfaat.<br /><br />Link:<br />1. <a href="http://astronomy.case.edu/steven/temp/olympiad/2008_C_olympiad_master.pdf">http://astronomy.case.edu/steven/temp/</a><br /> <a href="http://astronomy.case.edu/steven/temp/olympiad/2008_C_olympiad_master.pdf">olympiad/2008_C_olympiad_master.pdf</a><br />2. <a href="http://olympiads.hbcse.tifr.res.in/uploads/inao-jr-ans">http://olympiads.hbcse.tifr.res.in/uploads/inao-jr-ans</a><br />3. <a href="http://www.ioaa2009.ir/node/21">Soal - Soal dari Ajang 2nd dan 3rd IOAA</a><br /><br /><br /><a href="http://www.ioaa2009.ir/node/21"></a>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-7269849076521015772010-01-24T16:30:00.003+07:002010-01-24T16:34:32.573+07:00Oposisi Mars 2010<div style="text-align: justify;">Beberapa tahun yang lalu, mungkin ada yang masih ingat, ketika ramai dibicarakan bahwa Mars akan mendekati Bumi dengan ukuran sebesar Bulan, tentunya tidak!<br /><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhG3ZdsvV3MOsv52_SHDC8qeFSR4HY8T1tE9AVMNjzdj9qCZtAgM9D8SFkDzfWi11bYtoeEvovaCpZPGQusO5fpMpgLZfaiEtF1ckDqhqPCOT5vSDk9g6RiKSd_ed5wT7HoGTGwQIQza03/s1600-h/orbitmars.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 300px; height: 250px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhG3ZdsvV3MOsv52_SHDC8qeFSR4HY8T1tE9AVMNjzdj9qCZtAgM9D8SFkDzfWi11bYtoeEvovaCpZPGQusO5fpMpgLZfaiEtF1ckDqhqPCOT5vSDk9g6RiKSd_ed5wT7HoGTGwQIQza03/s400/orbitmars.jpg" alt="" id="BLOGGER_PHOTO_ID_5430237046892575362" border="0" /></a><span style="font-weight: bold;font-size:85%;" >Oposisi Mars dilihat dari arah kutub. Kredit : ESA</span><br /></div><br />Memang benar bahwa dalam lintasannya mengitari Matahari, baik Bumi dan Mars pada suatu ketika berada pada suatu posisi yang saling mendekat satu sama lain, karena lintasan Bumi, Mars, tidaklah merupakan lingkaran sempurna, tetapi berupa lintasan elips, dengan Matahari berada pada salah satu titik fokus elips.<br /><br />Bumi bergerak mengitari Matahari lebih cepat daripada Mars, dan setiap 26 bulan, Bumi akan mendahului Mars melalui lintasan dalam, dan ketika itu, saat Matahar-Bumi-Mars berada pada segaris, dikenal sebagai oposisi Mars. Maka, oposisi Mars akan selalu terjadi setiap 26 bulan, dan biasanya di waktu oposisi tersebut maka, Bumi dan Mars berada pada posisi yang saling berdekatan.<br /><br />Simulasi posisi Bumi-Mars & Matahari dapat dilihat di <a href="http://www.windows.ucar.edu/tour/link=/mars/mars_orbit.html">sini</a>.<br /><br />Jarak antara Bumi dan Mars tidak selalu sama setiap oposisi, karena orbit Mars yang sedikit lebih lonjong, maka jarak terdekat antara Bumi dan Mars tidak selalu tepat saat oposisi, tetapi selalu berada di sekitar waktu oposisi, yang berselisih beberapa hari dari waktu oposisinya. Dan biasanya, pada saat saling mendekat itu, maka Mars akan tampak cerlang dan cerlang, lebih kemerahan, kelihatan lebih jelas, baik diamati mempergunakan mata, binokular ataupun teleskop, tetapi yang pasti, tidak akan mencapai sebesar Bulan!<br /><br />Oleh karena bentuk geometri yang unik itu, maka setiap terjadi jarak yang terdekat antara Bumi-Mars (yang berperiode 26 bulan itu), tidak akan pernah sama dari satu kejadian ke kejadian berikutnya. Pada kejadian oposisi Mars tahun 2003, yang dikenal sebagai peristiwa Mars dalam posisi paling dekat (sedekat-dekatnya) dengan Bumi, jarak yang terhitung sebagai terdekat adalah 55758006 km, dengan diameter tampak sekitar 25″; dan fenomena ini hanya bisa terjadi setiap 60 ribu tahun. Besarkah itu? Bagi yang beruntung mengamati saat itu, Mars masih tetap sama seperti Mars yang telah diamati nenek moyang kita, dengan mata telanjang, masih berupa noktah merah terang di langit. Bahkan dengan teleskop sekalipun, tidak banyak berubah kenampakannya, hanya, detilnya agak lebih tampak sedikit.<br /><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqWX7QePkcd7l1q6fRuIYSG_tc7vs1_Q28W0sLc0y1np-e3MiBoZzdcyWXUz39lml6jzJi6NC5l0bGTx4Vegyo411DuDmW20SBGp2iCBkRRHWeM8MGU63gReh_mkuqrW-1hbUhyphenhyphenxjhA-tu/s1600-h/oposisimars.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 400px; height: 266px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqWX7QePkcd7l1q6fRuIYSG_tc7vs1_Q28W0sLc0y1np-e3MiBoZzdcyWXUz39lml6jzJi6NC5l0bGTx4Vegyo411DuDmW20SBGp2iCBkRRHWeM8MGU63gReh_mkuqrW-1hbUhyphenhyphenxjhA-tu/s400/oposisimars.jpg" alt="" id="BLOGGER_PHOTO_ID_5430237041733963378" border="0" /></a><span style="font-weight: bold;font-size:85%;" >Mars jelang oposisi yang dipotret Hubble sejak tahun 1995 - 2007. Kredit : NASA/Hubble</span><br /></div><br />Dan kemudian, di awal tahun 2010 ini, melalui siklus 26-bulan berikutnya (sesudah 2007), maka si merah kembali mendekat dengan Bumi! Di bulan Januari ini, Mars telah mencapai kecerlanganan mencapai sekitar -1 magnitudo, cukup terang teramati di langit sebagai suatu noktah merah yang jelas terlihat mempergunakan mata telanjang. Pada tanggal 27 Januari 2010, posisi terdekatnya mencapai 99 juta km, dengan diameter tampak sekitar 14″, lalu, oposisi Mars tercapai pada tanggal 29 Januari 2010, dengan magnitudo mencapai -1,28. Mars akan berada dalam kondisi yang sangat cerlang dengan magnitudo di sekitar -1, sampai dengan tanggal 14 Februari 2010, dan sesudah itu akan semakin meredup.<br /><br />Lalu, bagaimana kita menemukan Mars? Mudah, di bulan-bulan ini, ketika sore, carilah ke arah terbit di timur, apabila ada sebuah noktah yang cerlang berwarna kemerahan, besar kemungkinan itulah dia. Apabila kita telah mengetahui tentang rasi-rasi di langit, (mempergunakan peta langit sangat membantu), carilah rasi Cancer, maka disitulah ia berada!<br /><br /><span style="font-weight: bold;">Sumber: </span><a style="font-weight: bold;" href="http://langitselatan.com/2010/01/19/ketika-mars-kembali-mendekati-bumi-di-tahun-2010-dan-bukan-yang-hoax/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+langitselatan+%28langitselatan.com%29">Langit Selatan</a></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7835130099283684649.post-2551747088826811422010-01-21T20:56:00.005+07:002010-01-21T21:03:23.843+07:00The Known Universe<div style="text-align: justify;"><br /><center><object height="324" width="400"><param name="movie" value="http://www.youtube.com/v/17jymDn0W6U&color1=0xb1b1b1&color2=0xcfcfcf&hl=en_US&feature=player_embedded&fs=1"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/17jymDn0W6U&color1=0xb1b1b1&color2=0xcfcfcf&hl=en_US&feature=player_embedded&fs=1" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="324" width="400"></embed></object></center><br />What would it look like to travel across the known universe? To help humanity visualize this, the American Museum of Natural History has produced a modern movie featuring many visual highlights of such a trip. The video starts in Earth's Himalayan Mountains and then dramatically zooms out, showing the orbits of Earth's satellites, the Sun, the Solar System, the extent of humanities first radio signals, the Milky Way Galaxy, galaxies nearby, distant galaxies, and quasars. As the distant surface of the microwave background is finally reached, radiation is depicted that was emitted billions of light years away and less than one million years after the Big Bang. Frequently using the Digital Universe Atlas, every object in the video has been rendered to scale given the best scientific research in 2009, when the video was produced. The film has similarities to the famous <a href="http://www.powersof10.com/">Powers of Ten</a> video that has been a favorite of many space enthusiasts for a generation.<br /><br /><center><object height="324" width="400"><param name="movie" value="http://www.youtube.com/v/A2cmlhfdxuY&hl=en_US&fs=1&"><param name="allowFullScreen" value="true"><param name="allowscriptaccess" value="always"><embed src="http://www.youtube.com/v/A2cmlhfdxuY&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="324" width="400"></embed></object></center><br />Source: APOD<br /><br /></div>Unknownnoreply@blogger.com0