Tata Surya dan Jagat Raya/Solar System and the Universe FOR CLASS X SENIOR HIGH SCHOOL GEOGRAPHY
Tata Surya dan Jagat Raya
(Sumber: Sudibyakto, H. A. 2009. Geografi.Jakarta: Departemen Pendidikan Nasional.)
A) Jagat Raya
1) Teori terjadinya Jagat Raya
a) Teori “Big Bang”. Salah satu teori yang menjelaskan proses terjadinya jagat raya adalah teori “Big Bang”. Menurut teori ini, jagat raya terbentuk dari ledakan yang dahsyat yang terjadi kira-kira 13.700 juta tahun yang lalu. Akibat ledakan tersebut materi dengan jumlah sangat banyak terlontar ke segala penjuru alam semesta. Materi tersebut akhirnya membentuk bintang, planet, debu kosmis, asteroid, meteor, energy, dan partikel lain.
Teori “Big Bang” ini didukung oleh seorang astronom dari Amerika Serikat yaitu Edwin Hubble. Berdasarkan pengamatan dan penelitian yang dilakukan, menunjukkan bahwa jagat raya ini tidak bersifat statis. Semakin jauh jarak galaksi dari Bumi, semakin cepat proses pengembangannya. Penemuan tersebut dikuatkan lagi oleh ahli astro fisika dari Amerika Serikat, Arno Penzias dan Robert Wilson pada tahun 1965 telah mengukur tahap radiasi yang ada di angkasa raya. Penemuan ini kemudian disahkan oleh ahli sains dengan menggunakan alat NASA yang bernama COBE Spacecraft antara tahun 1989-1993. Kajian terkini dari laboratorium CERN (Camseil European pour la Recherche Nuclear atau European Council for Nuclear Research) yang terletak berdekatan dengan Geneva menguatkan lagi teori “Big Bang”. Semua ini mengesahkan bahwa pada masa lalu langit dan Bumi pernah bersatu sebelum akhirnya terpisah seperti sekarang.
b) Teori “Keadan Tetap”. Teori “keadaan tetap” atau teori ciptaan sinambung menyatakan bahwa jagat raya selama berabat selalu dalam keadaan yang sama dan zat hydrogen senantiasa diciptakan dari ketiadaan. Penambahan jumlah zat, dalam teori ini memerlukan waktu yang sangat lama yaitu kira seribu juta tahun untuk satu atom dalam satu volume ruang angkasa. Teori ini diajukan oleh ahli astronomi Fred Hoyle dan beberapa ahli astro fisika Inggris.
Dalam teori “keadaan tetap”, kita harus menerima bahwa zat baru selalu dicipatakan dalam ruang angkasa di antara berbagai galaksi sehingga galaksi baru akan terbentuk guna menggantikan galaksi yang menjauh. Orang sepakat bahwa zat yang merupakan asal mula bintang dan galaksi tersebut adalah hydrogen.
Teori ini diterima secara skeptic oleh beberapa ahli yang lain sebab hal itu melanggar salah satu hukum dasar fisika yaitu hukum kekekalan zat. Zat tidak dapat diciptakan atau dihilangkan tetapi hanya dapat diubah menjadi jenis zat lain atau menjadi energy.
Sampai saat ini belum dipastikan bagaimana sesungguhnya jagat raya ini terbentuk. Teori yang dikemukakan para ahli tersebut tentu memiliki kelebihan dan kekurangan sendiri-sendiri.
2) Anggapan tentang Jagat Raya dan Semesta
a) Anggapan Antroposentris atau Egoposentris (manusia pusat dari alam semesta). Anggapan ini dimulai pada tingkat awal manusia atau pada masa manusia primitive yang menganggap bahwa manusia sebagai pusat alam semesta. Pada waktu menyadari ada Bumi dan langit, manusia menganggap matahari, bulan, bintang dan Bumi serupa dengan hewan, tumbuhan dan dengan dirinya sendiri.
b) Anggapan Geosnetris (bumi pusat dari alam semesta). Anggapan ini menempatkan Bumi sebagai pusat dari alam semesta. Geosentris (geo= Bumi; centrum= titik pusat). Anggapan ini dimulai sekitara abad VI Sebelum Masehi, saat pandangan egosentris mulai ditinggalkan. Salah seorang yang mengemukakan anggapan geosentris adalah Claudius Ptolomeus. Ia melakukan observasi di Alexandria, kota pusat budaya Mesir pada masa lalu. Ia menganggap bahwa pusat jagat raya adalah Bumi sehingga Bumi ini dikelilingi oleh matahari dan bintang-bintang.
c) Anggapan Heliosentris (matahari pusat alam semesta). Semakin majunya alat penelitian dan sifat ilmuwan yang semakin kritis, menyebabkan bergesernya anggapan geosentris. Pandangan heliosentris (helios=matahari) dianggap sebagai pandangan yang revolusioner yang menempatkan matahari sebagai pusat alam semesta.
Seorang mahasiswa kedokteran, ilmu pasti dan Astronomi, Nicholas Copernicus (1473-1543) pada tahun 1507 menulis buku “De Revolutionibuss Orbium Caelestium” (tentang revolusi peredaran benda langit). Ia mengemukakan bahwa matahari merupakan pusat jagat raya yang dikelilingi planet, bahwa bulan mengelilingi Bumi dan bersama-sama mengitari matahari, dan bahwa Bumi perputar ke timur yang menyebabkan siang dan malam.
d) Anggapan Galaktosentris (galaksi sebagai pusat alam semesta). Galaktosentris (Galaxy=kumpulan jutaan bintang) merupakan anggapan yang menempatkan galaksi sebagai pusat Tata Surya. Galaktosentris dimulai tahun 1920 yang ditandai dengan pembangunan teleskop raksasa di Amerika Serikat, sehingga dapat memberikan informasi yang lebih banyak mengenai galaksi.
B) Galaksi dalam Jagat Raya.
1) Pengertian Galaksi. Para ahli astronomi menyimpulkan bahwa galaksi yang terdapat di alam semesta ini berjumlah miliaran dengan tiap galaksi terdiri atas ratusan miliar bintang. Untuk dapat mengamati apalagi menghitungnya, tentu tidak dapat melihat dengan menggunakan mata telanjang, perlu alat bantu yang disebut teleskop.
Galaksi adalah suatu sisitem bintang atau tatanan bintang-bintang. Galaksi tersusun secara menggerombol dan tiap anggota galaksi memiliki gaya tarik menarik (gravitasi). Matahari bersama planet yang mengitarinya pada sebuah galaksi yang diberi nama galaksi Bimasakti.
Galaksi Bimasakti termasuk galaksi spiral dan berbentuk seperti cakram, garis tengahnya kira-kira 100.000 tahun cahaya. Istilah tahun cahaya menggambarkan jarak yang ditempuh oleh cahaya dalam waktu satu tahun. Dengan kecepatan 300.000 km/detik, dalam waktu satu tahun cahaya akan ditempu jarak sekitar 9,5 triliun kilometer. Jadi, satu tahun cahaya adalah 9,5 triliun km. ini berarti garis tengah galaksi kita sekitar 100.000X9,5 triliun km atau 950 bilium km (950 diikuti dengan 15 buah nol dibelakangnya). Luar biasa jauhnya bukan? Untuk memudahkan perhitungan maka digunakan satuan jarak yaitu tahun cahaya. Dengan satuan ini, tebal bagian pusat galaksi kita sekitar 10.000 tahun cahaya.
Lalu, dimana letak Matahari kita? Matahari terletak sekitar 30.000 tahun cahaya dari pusat Bimasakti. Matahari bukanlah bintang yang istimewa, tetapi hanyalah salah satu dari 200 miliar buah bintang anggota Bimasakti. Bintang anggota Bimasakti ini tersebar dengna jarak dari satu bintang ke bintang lain berkisar 4 sampai 10 tahun cahaya. Semakin kea rah pusat galaksi, jarak antarbintang semakin dekat atau dengan kata lain kerapatan galaksi ke arah pusat semakin besar.
| Galaksi (Galaxy) | Jarak dari Bumi (Tahun Cahaya)/ distance from Earth (light years) |
| Magellan | 180.00 |
| Andromeda (M31) | 2.200.000 |
| M32 | 2.300.000 |
| Triangulum (M33) | 2.400.000 |
| Wolf-Lundmark | 4.290.000 |
| M81 | 9.450.000 |
| Centaurus A | 13.040.000 |
| Pinwheel (M101) | 23.790.000 |
| Whirlpool (M51) | 29.340.000 |
| NGC2841 | 37.490.000 |
| NGC1023 | 39.120.000 |
| NGC3184 | 42.380.000 |
| NGC5866 | 42.380.000 |
| M100 | 48.900.000 |
| NGC6643 | 74.980.000 |
| M77 | 81.500.000 |
| NGC3938 | 94.540.000 |
| NGC2207 | 114.100.000 |
| NCG205 | 2.200.000 |
(Beberapa galaksi yang dekat dengan Bumi)
Jumlah keseluruhan galaksi yang dapat dipotret dengan teleskop berdiameter 500 cm di Gunung Palomar, Amerika Serikat, diperkirakan mencapai satu miliar buah galaksi. Jika menggunakan teleskop yang besar tentunya kita dapat melihat galaksi yang jauh lebih banyak lagi dan dengan jarak yang lebih jauh lagi dibandingkan dengan galaksi yang telah diketahui selama ini.
2) Bentuk Galaksi.
Menurut morfologinya galaksi dibagi menjadi tiga tipe, yaitu tipe galaksi spiral, elips dan tidak beraturan. Pembagian tipe ini berdasarkan betuk atau penampakan galaksi tersebut. Hasil pengamatan para astronom menunjukkan bahwa galaksi yang terdapat di jagat raya ini terdiri atas 75% galaksi spiral, 20% galaksi elips dan 5% galaksi tak beraturan. Walaupun begitu, galaksi elips diyakini merupakan tipe galaksi yang paling banyak terdapat di jagat raya ini. Jika kita mengambil volume ruang angkasa yang sama, kita akan menemukan lebih banyak galaksi elips daripada galaksi spiral. Hanya saja galaksi tipe ini banyak yang terlihat begitu redup sehingga amat sulit untuk diamati.
a) Galaksi Tak beraturan. Galaksi ini tidak memiliki bentuk khusus. Anggota dari galaksi ini terdiri atas bintang tua dan muda. Contoh dari galaksi tipe ini adalah Awan Magellan Besar dan Awan Magellan Kecil, dua buah galaksi tetangga yang terdekat dengan Bimasakti yang hanya berjarak sekitar 180.000 tahun cahaya dari Bimasakti. Galaksi tak beraturan ini banyak mengandung materi antar bintang yang terdiri atas gas dan debu.
b) Galaksi Elips. Penampakan galaksi ini terliaht seperti elips. Galaksi yang termasuk dengan tipe elips ini mulai dari galaksi yang berbentuk bundar sampai galaksi yang berbentuk bola pepat. Struktur galaksi tipe ini tidak terlihat dengan jelas. Galaksi elips sangat sedikit mengandung materi antar bintang dan anggotanya adalah bintang tua. Contoh galaksi tipe ini adalah galaksi M87, yaitu galaksi elips raksasa yang terdapat di Rasi Virgo.
c) Galaksi Spiral. Bagian utama galaksi spiral adalah halo, bidang galaksi (termasuk lengan spiral) dan bulge (bagian pusat galaksi yang menonjol). Anggota galaksi spiral terdiri atas bintang tua dan muda. Bintang tua terdapat pada kumpulan bintang yang berjumlah ratusan dan berbentuk bola (gugusan bola). Bintang muda terdapat di lengan spiral galaksi yang berada di bidang galaksi. Galaksi spiral berotasi dengan cepat sehingga membuat galaksi ini memipih dan membentuk bidang galaksi. Contoh dari tipe galaksi tipe ini adalah galaksi Andromeda dan galaksi Bimasakti. Di galaksi Bimasakti inilah Bumi sebagai bagian dari system Tata Surya berada.
C) Tata Surya
1) Teori terjadinya Tata Surya
a) Teori Nebula (oleh Immanuel Kant dan Marquis de Laplace). Teori ini mengatakan bahwa anggota keluarga Tata Surya pada awalnya berbentuk massa gas raksassa yang bercahaya dan berputar perlahan. Massa ini berangsur mendingin, mengecil, dan mendekati bentuk bola. Rotasi massa ini semakin lama semakin tinggi. Akibatnya bagian tengah massa itu menggelembung. Akhirnya lingkaran materi ini terlempar keluar. Lingkaran ini mendingin, mengecil dan akhirnya menjadi planet.
Planet ini tetap mengorbit mengelilingi inti massa. Lalu, lingkaran lain terlempar lagi dari pusat massa dan menjadi seluruh planet, termasuk Bumi. Akhirya semua planet terbentuk. Pusat massa menjadi matahari kita. Selanjutnya, planet itu juga melemparkan masa keluar angkasa dan berubah menjadi satelit atau bulan.
b)Teori Planetesimal (oleh Forest Ray Moulton dan T. C. Chamberlain). Teori ini menyatakan bahwa suatu ketika sebuah bintang melintasi ruang angkasa dengan cepat dan berada dekat sekli dengan matahari. Daya tarik bintang ini sangat besar sehingga menyebabkan pasang di bagian gas panas matahari. Akibatnya, massa gas terlempar dari Matahari dan mulai mengorbit. Karena daya tarik matahari, massa gas itu tertahan dan bergerak mengelilingi matahari. Ketika massa gas menjadi dingin, bentuknya berubah menjadi cairan kemudian memadat. Akhirnya massa gas itu menjadi planet yang ada sekarang, termasuk Bumi.
c) Teori Pasang (oleh Sir James Jeans dan Sir Harold Jeffreys). Teori ini juga didasarkan ide benturan. Teori ini mengatakan bahwa planet terbentuk langsung oleh gas asli yang tertarik oleh sebuah bintang yang melintas di dekatnya. Jadi, teori ini awalnya hampir sama dengan teori Planetesimal. Perbedaan bahwa teori ini planet tidak terbentuk oleh planetesimal. Menurut teori ini, ketika bintang mendekat atau bahkan menyerempet Matahari, tarikan gravitasinya menyedot filament gas yang berbentuk cerutu panjang. Filament yang membesar di bagian tengahnya mengecil di kedua ujungnya, filament inilah akhirnya yang membentuk sebuah planet.
d) Teori Lyttleton (oleh R. A. Lyttleton). Teori ini mengatakan bahwa Matahari mulanya berupa bintang kembar yang mengelilingi sebuah medan gravitasi. Sebuah bintang menabrak salah satu bintang kembar dan mungkin menghancurkannya. Bintang yang hancur itu berubah menjadi massa gas yang berputar. Karena terus berputar, gas ini menjadi dingin terbentuk planet.
Adapun bintang yang bertahan, menjadi Matahari kita. Karena kekuatan gravitasinya, Matahari menahan planet yang terbentuk dan beredar menurut lintasannya sekarang. Jadi, jelaslah bahwa teori ini juga didasarkan ide benturan.
c) Teori Awan Debu (Fred L. Whippel). Teori ini mengatakan bahwa calon Tata Surya semula merupakan awan yang sangat luas. Awan yang terdiri atas debu dan gas kosmos itu diperkirakan berbentuk seperti sebuah piring. Ketidak teraturan dalam awan itu menyebabkan terjadinya perputaran. Debu dan gas yang berputar berkumpul menjadi satu. Sementara debu dan gas itu terus berputar, hilanglah awannya.. partikel debu yang keras saling berbenturan, melekat dan kemudian menjadi planet. Berbagai gas yang terdapat di tengah awan berkembang menjadi matahari.
Teori di atas hanyalah sedikit dari banyak teori yang telah diajukan para ahli tentang terjadinya Bumi. Tidak ada satu pun di antara teori tersebut yang dianggap benar memuaskan dan diterima secara luas oleh seluruh dunia. Masing teori ini mempunyai kelebihan dan kekurangna. Namun demikian, kita hrus mengetahui bahwa teori tersebut dikemukakan berdasarkan penelitian, pengamatan, dan perhitungan yang matang. Kita harus menghargai buah pikiran mereka.
2) Anggota Tata Surya
a) Matahari. Matahari adalah pusat Tata Surya. Ukuran garis tengah Matahari adalah seratus kali lebih besar dari Bumi. Walaupun begitu, untuk ukuran jagat raya Matahari termasuk bintang kecil. Masih ada bintang yang besarnya seratus dari Matahari.
Jarak Matahari ke Bumi sekitar 150 juta kilometer. Jarak Matahari ke bumi disebut satu satuan astronomi (1 sa). Waktu yang dibutuhkan oleh sinar matahari untuk sampai ke bumi 8,33 menit.
Matahari terdiri atas bagian inti dan lapisan kulit. Bagian kulit Matahari terdiri atas lapisan fotosfera, khromosfera, dan korona. Fotosfera merupakan gas yang dipancarkan ke segala penjuru. Di atas fotosfera terdapat lapisan khromosfera. Korona berada pada bagian terluar matahari, berupa lidah api yang menyala.
Seperti halnya bintang lainnya, matahari mengeluarkan energy hasil reaksi nuklir yang sangat dahsyat. Pancaran energy hasil reaksi nuklir pada bagian inti menghasilkan panas sebesar 15.000.000 oC. Bandingkan dengan suhu pada permukaan yang hanya 6.000 oC. Sungguh luar biasa panas. Oleh karena itu di dalam Matahari tidak ada benda padat. Semuanya berupa gas.
b) Planet. Planet merupakan benda langit dalam Tata Surya yang bergerak mengelilingi matahari pada lintasan (orbit) yang stabil. Memang dahulu, kita mengenal Sembilan planet yaitu Merkurius, Venus, Bumi, Mars, Yupiter, Saturnus, Uranus, Neptunus dan Pluto. Tetapi saat ini yang diakui sebagai planet anggota Tata Surya hanya delapan kecuali Pluto. Mengapa hal ini bisa terjadi?
Sidang Umum Perkumpulan Astronomi Internasional (International Astronomical Union/ IAU) ke 26 yang berlangsung di Praha, Republik Ceko, pada tanggal 25 Agustus 2006 telah memutuskan beberapa keputusan yang penting, di antaranya adalah resolusi 5A yang berisi mengenai definisi sebuah planet. Suatu benda angkasa dapat disebut sebagai planet apabila memiliki syarat sebagai berikut:
i) Berada dalam suatu orbit yang mengelilingi matahari.
ii) Mempunyai berat yang cukup untuk gravitasi dirinya dalam mengatasi tekanan rigid supaya ia menjadi satu ekuilibrium hidrostatik (bentuk hampir bulat).
iii) Merupakan obyek yang dominan dalam orbitnya sendiri
Berdasarkan definisi Pluto hasil sidang (International Astronomical Union) IAU, Pluto tidak memenuhi syarat sebagai sebuah planet karena Pluto memiliki orbit yang tumpang tindih dengan Neptunus. Hal ini menunjukkan Pluto sebagai sebuah obyek yang tidak dominan di orbitnya sendiri. Pluto yang telah menyandang status planet sejak ditemukan oleh Clyde Tombaugh pada tahun 1930, akhirnya harus kehilangan status sebagai sebuah planet. Saat ini yang diakui sebagai planet dalam system Tata Surya tinggal delapan planet yaitu Merkurius, Venus, Bumi, Mars, Yupiter, Saturnus, Uranus dan Neptunus.
Ø Planet Merkurius. Merkurius merupakan planet terdekat dengan Matahari. Kedekatan ini mengakibatkan suhu di Merkurius sangat panas. Panas hari di Merkurius sangat tinggi, konon mampu melelehkan timah yang melapisi kaleng. Jarak antara Matahari dengan Merkurius kurang lebih 57 juta km. sedangkan jarak dengan Bumi sekitar 92 juta km. ukuran hanya 27% dari ukuran Bumi. Merkurius mengelilingi matahari (revolusi) memerlukan waktu 88 hari sedangkan rotasinya memerlukan waktu 59 hari. Planet tersebut begitu lambang berputar sehingga satu hari hampir sama lamanya dengan satu tahun di Bumi.
Ø Planet Venus. Planet terdekat kedua dari Matahari adalah Venus. Salah satu yang khas dari planet ini adalah adanya awan tebal yang menyelimutinya. Awan itu membuat cahaya Matahari terpantulkan. Akibatnya, Venus menjadi planet yang paling terang. Cahaya yang akan tampak pada waktu Matahari terbit dan tenggelam. Oleh karenanya, planet inisering disebut sebagai Bintang Fajar atau Bintang Senja. Venus juga merupakan planet yang paling dekat dengan Bumi. Jarak Venus dengan matahari sekitar 108 juta kilometer. Satu tahun di Venus sama dengan 225 hari di Bumi. Sedangkan satu hari di sana sama dengan 243 hari di Bumi. Dengan demikian masa revolusinya lebih cepat dibandingkan masa rotasinya.
Ø Planet Bumi. Jagat raya memang sangat luas, Bumi hanyalah sebagian kecil darinya. Jika melihat kenyataan ini, mungkin saja masih ada kehidupan lain di jagat raya tetapi untuk lingkup Tata Surya hanya Bumilah yang diyakini mempunyai kehidupan yang sangat berkembang. Bumi seperti planet yang lain, tidak memiliki cahaya. Bumi pun mempunyai satelit seperti planet lainnya yakni bulan sebagai satelit alami Bumi, mempunyai gerakan mengelilingi Bumi dengan waktu putaran 29,5 hari. Bumi mempunyai masa rotasi sekitar 23 jam 56 menit dan memiliki masa revolusi sekitar 365 hari 6 jam.
Ø Planet Mars. Planet Mars adalah planet terluar yang paling dekat dengan bumi. Pada malam hari kadang kita melihat sebuah “planet” cemerlang yang bercahaya kemerahan. Itulah Mars atau planet merah. Namanya berasal dari nama dewa Perang Romawi. Planet ini memiliki diameter kira 6.800 km atau sekitar setengah diameter Bumi. Masa rotasi Mars adalah 24 jam 37 menit dan masa revolusinya 687 hari. Mars memiliki dua buah satelit yaitu Deimos dan Phobos, temperaturnya di Bumi.
Ø Planet Yupiter. Planet Yupiter adalah planet terbesar yang ada di dalam Tata Surya. Jika kita bayangkan Yupiter sebagai wadah, maka ia mampu menampung sebanyak 1310 planet seukuran Bumi. Tetapi tidak sebanding dengan besarnya, berat Yupiter hanya setengah kali Bumi. Planet ini lembek, permukaan hanya berupa gas helium dan hydrogen cair yang terbungkus oleh awan yang bergerak. Keunikan lain yang dimiliki Yupiter yaitu rotasi yang paling cepat, hanya membutuhkan 10 jam. Sedangkan masa revolusinya membutuhkan waktu yang sangat lama yaitu 12 tahun.
Ø Planet Saturnus. Planet keenam dalam tata surya mempunyai keunikan, dikelilingi dengan cincin yang terbentuk dari potongan jutaan es. Jarak Saturnus dengan Matahari sekitar 1,4 miliar kilometer. Masa revolusinya sekitar 30 tahun, sedangkan masa rotasinya sekitar 10,5 jam. Planet ini mempunyai sifat seperti Yupiter, keduanya berputar begitu cepat sehingga dianggap sebagai planet yang paling berangin. Kecepatan anginnya lebih dari 10 kecepatan angin Hurricane di Bumi.
Ø Planet Uranus. Uranus ditemukan oleh William Herschel pada tahun 1782 dengan bantuan teleskop di kebun belakang rumahnya di Bath, Inggris. Planet ini merupakan salah satu planet yang jauh dari Matahari. Terdiri atas gas utama yang berupa hydrogen, metana dan helium serta mengandung gas. Keadaan ini membuat Uranus dingin dan beku. Seperti halnya Saturnus, Uranus juga mempunyai cincin. Cincin Uranus tipis dan hingga saat ini telah ditemukan Sembilan lapis cincin Uranus. Keunikan lain yang juga dimiliki oleh planet ini, rotasinya yang berlawanan dengan arah rotasi Bumi membuat salah satu sisinya seperti sebuah gasing yang rebah. Masa revolusi Saturnus sekitar 84 tahun dan masa rotasinya sekiar 11 jam. Akibatnya satu sisi planet terus menerus mengalami siang selama 42 tahun sedangkan sisi lain terus menerus mengalami malam selama 42 tahun.
Ø Planet Neptunus. Kondisi di Neptunus tidak berbeda jauh dari Uranus, terdiri atas gas. Ukuran Neptunus juga besar meskipun tidak sebesar Yupiter. Jika diumpamakan wadah kosong, Neptunus mampu menampung 60 planet seukuran Bumi. Satu tahun di Neptunus sama dengan 165 tahun di Bumi sedangkan satu hari di sana sekitar 16 jam di Bumi. Sejak tahun 1984, para ahli telah menduga bahwa Neptunus mempunyai cincin.
c) Planet Kerdil atau Planet Katai (Dwarf Planet). Selain mendefinisikan sebuah planet, hasil resolusi IAU yang berlangsung di Praha juga mendefinisikan tentang “dwarf planet” atau planet kerdil. Syarat pendefinisian “dwarf planet” atau planet kerdil hampir sama dengan definisi planet. Yang membedakan adalah “dwarf planet” atau planet kerdil bukan benda dominan pada orbitnya serta bukan satelit (benda angkasa yang mengorbit planet). Pluto yang dahulunya masuk deretan planet di Tata Surya, statusnya diubah sebagai “dwarf planet” atau planet kerdil. Bersamaan dengan Pluto sebagai objek yang berada disekitar Pluto dikategorikan sebagai “dwarf planet” atau planet kerdil yaitu asteroid Ceres, 2003 UB313 (ditemukan oleh Mike Brown dari Institut Teknologi California dengan samaran ‘Xena’) dan bulan terbesar di Pluto yang disebut Charon.
d) Asteroid. Asteroid merupakan planet berbatu yang kecil (diameter 1.700 km) dengan jumlah yang sangat banyak. Dalam tata surya terdapat beribu asteroid yang juga mengelilingi matahari. Asteroid yang orbitnya melewati orbit bumi dinamakan asteroid Apollo. Selain itu, banyak di antara asteroid yang sudah diberi nama sesuai dengan nama penemunya.
Sebagian besar kelompok asteroid dijumpai berada di antara orbit planet Mars dan Yupiter. Daerah ini dikenal sebagai Sabuk Utara (Main Belt). Selain asteroid yang mendiami daerah Sabuk Utama, ada pula kelompok asteroid dengan orbit yang berbeda seperti kelompok Trojan dan kelompok asteroid AAA (Triple A Asteroid-Armor, Apollo, Alen).
e) Meteor. Ketika kita melihat sejenak ke langit yang cerah pada malam hari, tampak seberkas cahaya yang bergerak cepat lalu menghilang. Itulah meteor. Meteor atau disebut juga bintang jatuh merupakan bagian dari asteroid yang terpisah. Meteor yang jatuh mengarah ke Bumi akan tampak seperti bola api.
Meteor yang jatuh terkadang sangat banyak dan disebut sebagai hujan meteor. Ketika terjadi hujan meteor, jutaan meteor masuk ke dalam atmosfer bumi, tetapi sebagian besar terbakar habis sebelum mencapai permukaan bumi. Kadang meteor yang besar tidak terbakar habis dan akhirnya sampai ke permukaan bumi dan disebut sebagai meteorit.
Meteor besar yang jatuh ke bumi akan membentuk kawah besar seperti kawah Barringer di wilayah Arizona. Kawah ini terbentuk oleh meteor yang jatuh kira 40.000 tahun yang lalu.
f) Komet. Komet merupakan benda angkasa yang terlihat bercahaya dikarenakan adanya gesekan atom di udara. Ukurannya dapat melebih 10 mil dan mempunyai ekor yang panjangnya jutaan mil. Oleh karena itu, komet sering disebut juga bintang berekor. Ciri khas komet adalah ekornya yang sangat panjang. Panjang bisa mencapai 100 juta km. inti komet disebut nucleus yang terdiri atas bongkahan es serta gas yang telah membeku. Diameter nucleus bisa mencapai 10 km. ekor merupakan bagian dari komet, berasal dari coma yang menyelimuti inti komet. Diameter coma bisa mencapai 100.000 km.
Salah satu komet yang terkenal adalah komet Halley. Komet ini ditemukan oleh Edmond Halley. Rata-rata periode munculnya orbit komet Halley terjadi setiap 76-79 tahun sekali. Komet Halley terakhir terlihat pada tahun 1986 dan diperkirakan akan tampak kembali pada tahun 2061. Inti atau pusat dari komet Halley sangatlah gelap dengan diameter kurang lebih 1.024 km.
Selain komet Halley terdapat beberapa nama komet lainnya, seperti komet Hyakutake dan Hale Bopp. Para ahli menyebutkan, pada 251 juta tahun yang lalu terjadi kepunahan yang sangat besar di sebabkan komet atau asteroid telah menabrak bumi. Kesimpulan itu diperoleh dari atom yang terjebak di dalam kerangka molekuler karbon. Tetapi belum diketahui di mana letak tempat tabrakan komet atau asteroid dengan bumi tersebut.
Tahukah Kamu?
Ø Tahukah kamu planet pemegang rekor? Planet terpanas yakni planet Venus dengan suhu 462oC, Bergerak paling cepat yakni Planet Merkurius dengan kecepatan 172.000 km/jam, Paling rapat yakni Bumi dengan kerapatan lima kali lebih rapat daripada air.
Ø Tamu dari Luar Angkasa. Bumi sejak jaman dahulu sering didatangi tamu dari luar angkasa berupa asteroid, meteor atau komet. Benda langit itulah yang diyakini menciptakan ekosistem di Bumi. Ribuan meteorit menghujani Bumi setiap tahunnya. Hanya saja karena ukurannya sangat kecil, meteor ini sudah hancur terbakar ketika memasuki atmosfer. Sebagian di antaranya mungkin masih tersisa dan jatuh ke Bumi berupa bola api (meteorit). Kejadian nyata apda tanggal 30 Juni 1908, ketika sebuah meteorit berdiameter hanya 60 meter meledak di ketinggian 15 kilometer di atas hutan di kawasan Tunguska Siberia. Dalam radius 60 kilometer rumah seolah diguncang gempa hebat. Pada radius sekitar 20 kilometer dari pusat ledakan, hutan terbakar dan porak poranda. Selain itu, para ahli memperkirakan musnahnya dinasaurus 65 juta tahun lalu akibat jatuhnya sebuah asteroid berdiameter 10 kilometer ke Semenanjung Yucatan di Meksiko.
IN ENGLISH (with google translate Indonesian-english):
Solar System and the Universe
(Source: Sudibyakto, HA 2009. Geografi.Jakarta: Ministry of Education.)
A) Universe
1) Theory of the Universe
a) The theory of the "Big Bang". One theory to explain the process of the universe is the theory of the "Big Bang". According to this theory, the universe is made up of a powerful explosion that occurred about 13 700 million years ago. The explosion of very large material ejected in all directions of the universe. The material was eventually form stars, planets, cosmic dust, asteroids, meteors, energy, and other particles.
The theory of the "Big Bang" was supported by a U.S. astronomer Edwin Hubble that. Based on observations and research conducted, showing that the universe is not static. The farther the galaxy's distance from Earth, the faster the process of development.The findings were further corroborated by an astro physicist from the United States, Arno Penzias and Robert Wilson in 1965 has measured the radiation phase is in space. The findings are then validated by scientists using NASA instrument called COBE Spacecraft between 1989-1993. Recent studies from the laboratory of CERN (European pour la Recherche Camseil Nuclear or European Council for Nuclear Research), located adjacent to Geneva reaffirms the theory of the "Big Bang". All this confirms that the past never unite heaven and earth before finally separated as they are now.
b) The theory of "objec Fixed". The theory of "steady state" or continuous creation theory states that the universe during berabat always in the same state and hydrogen substances ever created out of nothing. Increasing the number of agents, in this theory requires a very long time is a thousand million years to one atom in a volume of space. This theory was proposed by astronomer Fred Hoyle and some experts astro physics England.
In the theory of "steady state", we have to accept that a new substance is always dicipatakan in the space between galaxies that new galaxies are formed to replace a galaxy away. People agreed that the substance that is the origin of stars and galaxies is hydrogen.
This theory is accepted by some experts skeptical others because it violates one of the basic laws of physics is the law of conservation of matter. Matter can not be created or destroyed but can only be transformed into another substance or a type of energy.
It is not yet determined exactly how the universe was formed. The theory advanced by the experts certainly have their advantages and disadvantages on their own.
2) assumption about the Universe and the Universe
a) the assumption or Egoposentris anthropocentric (human center of the universe). This assumption is begun at the beginning of the human or in the primitive humans who consider that man as the center of the universe. At the time realized there was earth and sky, people assume the sun, moon, stars and Earth are similar to animals, plants, and with himself.
b) The presumption Geosnetris (earth center of the universe). This assumption puts the Earth as the center of the universe. Geocentric (geo = earth; centrum = center point). This assumption started sekitara VI century BC, when the egocentric view of becoming obsolete. One person suggested geocentric assumption is Claudius Ptolemy. He made observations at Alexandria, Egypt cultural center of the city in the past. He considered that the center of the universe is the Earth so that the Earth is surrounded by the sun and stars.
c) The presumption Heliocentric (sun center of the universe). More advanced research tools and the increasingly critical nature of scientists, led to the shifting perception geocentric. The views heliocentric (helios = sun) is considered as a revolutionary who put the sun as the center of the universe.
A student of medicine, science and Astronomy, Nicholas Copernicus (1473-1543) in 1507 wrote the book "De Revolutionibuss orbium Caelestium" (about the circulation of celestial revolutions). He argues that the sun is the center of the universe surrounded by planets, the moon around the Earth and together around the sun, and the Earth perputar eastward causing day and night.
d) The presumption Galaktosentris (galaxy as the center of the universe). Galaktosentris (Galaxy = a collection of millions of stars) is the presumption that places the galaxy at the center of the Solar System. Galaktosentris began in 1920 that was marked by the construction of a giant telescope in the United States, so as to provide more information about the galaxy.
B) Galaxies in the Universe.
1) Definition of the Galaxy. The astronomers concluded that the galaxies are in the universe with billions of galaxies each containing hundreds of billions of stars. To be able to observe the count moreover, would not be seen with the naked eye, need a tool called a telescope.
The galaxy is a star or order sisitem stars. Galaxies gather arranged and each member galaxy has attractive force (gravity).The sun with its planets in a galaxy called the Milky Way.
Including the Milky Way galaxy and a spiral-shaped like a disc, diameter of about 100,000 light years. The term describes light years distance traveled by light in one year. With a speed of 300,000 km / sec, within one year of light will ditempu distance of about 9.5 trillion miles. So, a light year is 9.5 trillion miles. This means the diameter of our galaxy about 100.000X9, 5 trillion km or 950 bilium km (950 followed by 15 zeros behind the fruit). Excellent away is not it? To simplify the calculations we used the light-year distance unit. With this unit, the thick central part of our galaxy about 10,000 light-years away.
So, where is our sun? The sun is located about 30,000 light years from the center of the Milky Way. The sun is not a star special, but just one of 200 billion pieces star member of the Milky Way. Stars Milky Way members are scattered dengna distance from one star to another star ranged from 4 to 10 light years. The more towards the center of the galaxy, interstellar distances closer or in other words, towards the center of the galaxy density increases.
(Some galaxies are close to the Earth)
The total number of galaxies that can be photographed with a diameter of 500 cm telescope at Mount Palomar, the United States, an estimated one billion pieces of galaxies. If using a large telescope of course we can see galaxies far more and with greater distances longer than the galaxy known so far.
2) Shape Galaxies.
According to the morphology of galaxies are divided into three types, namely type spiral galaxies, elliptical and irregular. The division is based on the type or appearance betuk galaxies.Observations astronomers showed that galaxies in the universe are made up 75% of spiral galaxies, 20% and 5% elliptical galaxies, irregular galaxies. However, elliptical galaxies are believed to be the type most numerous galaxies in the universe. If we take the same volume of space, we will find more elliptical galaxies than spiral galaxies. It's just that many galaxies of this type that looks so dim that it was difficult to observe.
a) No irregular galaxy. This galaxy has no particular form. Members of the galaxy is composed of young and old stars. Examples of this type of galaxy is the Large Magellanic Cloud and Small Magellanic Clouds, two neighboring galaxies closest to the Milky Way, which is only about 180,000 light-years from the Milky Way. Irregular galaxy contains a lot of interstellar matter consists of gas and dust.
b) Elliptical Galaxies. Sightings terliaht like elliptical galaxies.Galaxies are included with this type of elliptical galaxies ranging from circular to spherical galaxies pepat. The structure of this type of galaxy is not seen clearly. Elliptical galaxy contains very little interstellar matter and its members are old stars. Examples of this type of galaxy is the galaxy M87, a giant elliptical galaxy that is located in the constellation Virgo.
c) Spiral Galaxies. The main part is a spiral galaxy halo, the galactic plane (including the spiral arms) and the bulge (a prominent part of the galactic center). A spiral galaxy consists of young and old stars.Old stars found in a collection of hundreds of star-shaped ball (spherical clusters). Young stars in the spiral arms of galaxies are located in the galactic plane. Spiral galaxies rotate so fast that makes this galaxy flattened and form the galactic plane. Examples of this type of this type of galaxy is the Andromeda galaxy and the Milky Way. In the Milky Way galaxy is the Earth as part of the Solar system is located.
C) Solar System
1) The theory of the Solar System
a) Theory Nebula (by Immanuel Kant and the Marquis de Laplace).This theory says that family members initially shaped the Solar System raksassa a glowing mass of gas and rotates slowly. This mass gradually cooled, shrink, and approximates the shape of a ball. Rotation mass is higher and higher. As a result, the center of mass of that bubble. Finally loop material thrown out. The circle is cooled, shrink and eventually become planets.
The planet is still orbiting around the center of mass. Then, another circle was thrown away from the center of mass and a whole planet, including Earth. Ultimately all the planets formed. Center of mass to our sun. Furthermore, the planet is also the time threw out the sky and turned into a satellite or moon.
b) planetesimal theory (by Forest Ray Moulton and TC Chamberlain). This theory states that when a star crosses a space quickly and are close to the sun sekli. The star attraction is so great that it caused the gas plug in the hot sun. As a result, the mass of the Sun and the gas was thrown from orbit. Because the sun's appeal, held that the gas mass and moves around the sun. When the mass of the gas to cool, form into a liquid then solidifies. Finally, the mass of the gas into the existing planets, including Earth.
c) Put Theory (by Sir James Jeans and Sir Harold Jeffreys). This theory is also based on the idea of conflict. This theory says that planets are formed directly by the original gas attracted by a star passing nearby. Thus, this theory is almost the same as the theory originally planetesimals. The difference that this theory is not formed by planetesimal planet. According to this theory, when the star is approaching or even grazed the Sun, its gravitational pull suck gas cigar-shaped filament length. Filament enlarged in the middle, narrowed at both ends, these filaments eventually forming a planet.
d) Theory of Lyttleton (by R. A. Lyttleton). This theory says that the Sun first twin stars form around a gravitational field. A star hit one of the twin star and possibly destroy it. Stars who ruined it turned into a rotating mass of gas. Due to continued spinning, gas cools the planet formed.
The stars who survived, became our sun. Because of the strength of gravity, the Sun hold planets formed and circulated by its trajectory now. Thus, it is clear that this theory is also based on the idea of conflict.
c) Dust Cloud theory (Fred L. Whippel). This theory says that the candidate of the Solar System was originally a vast cloud. Clouds composed of dust and gas is expected cosmos is shaped like a plate. Irregularity of the cloud caused the turnaround. Dust and gas rotating gathered into one. While dust and gas it kept spinning, cloud disappears .. harsh dust particles collide with each other, and then attached to the planet. Various gases contained in the clouds develop into the sun.
Theories are just a few of the many theories that have been raised by experts about the Earth. There is no one among these theories are considered completely satisfactory and widely accepted by the whole world. Each of these theories has excess and lack. However, we hrus know that the theory put forward based on research, observation, and calculation. We must respect their thoughts.
2) Members of the Solar System
a) The sun. The sun is the center of the Solar System. Diameter size of the Sun is a hundred times larger than Earth. However, for the size of the universe, including the sun a little star. There is still an amount of one hundred stars from the Sun.
Distance of the Sun to the Earth about 150 million kilometers.Distance of the Sun to the Earth is called the astronomical unit (1 sa). The time taken by the sun to reach the earth 8.33 min.
The sun is made up of core and skin layers. The skin of the Sun consists of layers fotosfera, khromosfera, and corona. Fotosfera gas is emitted in all directions. At the top there is a layer fotosfera khromosfera. Corona is the outermost part of the sun, a flame is lit.
As with other stars, the sun emit energy nuclear reaction proceeds very powerful. Radiant energy yield of nuclear reactions in the core produce heat for 15 million oC. Compare the temperature at the surface only 6,000 oC. It was unbelievably hot. Therefore, in the sun there is no solid objects. Everything is in the form of gas.
b) Planet. Planets are celestial bodies in the solar system moves around the sun in the trajectory (orbit) are stable. It first, we know that nine planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. But now recognized as a member of the solar system planets except Pluto was only eight. Why does this happen?
General Assembly of the International Astronomical Society (International Astronomical Union / IAU) to 26 which took place in Prague, Czech Republic, on August 25, 2006 has decided several important decisions, among them the 5A resolution that contains the definition of a planet. A celestial body can be called a planet if it has the following requirements:
i) Being in an orbit around the sun.
ii) Having sufficient weight to overcome the pressure of gravity itself in rigid so that he became a hydrostatic equilibrium (nearly round shape).
iii) It is the dominant object in its own orbit
Based on the definition of Pluto outcome of the trial (International Astronomical Union) IAU, Pluto does not qualify as a planet because Pluto has an orbit that overlaps with Neptune's. It shows Pluto as an object that is not dominant in its own orbit. Pluto has the status of a planet since it was discovered by Clyde Tombaugh in 1930, eventually losing its status as a planet. Currently recognized as a planet in the Solar system is only eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Mercury. Mercury is the closest planet to the Sun. Proximity is the temperature on Mercury is very hot. Hot day at the Mercury is very high, supposedly able to melt tin cans lining. The distance between the Sun with Mercury approximately 57 million miles. while the distance to the Earth about 92 million miles. size of only 27% of the size of the Earth. Mercury around the Sun (revolution) took 88 days while the rotation takes 59 days. The planet rotates once a symbol that one day is almost the same length with a year on Earth.
Planet Venus. The second nearest planet from the Sun is Venus.One characteristic of the planet is a thick cloud enveloped him. The cloud makes terpantulkan sunlight. As a result, the planet Venus being the brightest. The light will appear when the sun rising and setting. Therefore, inisering planet known as the Morning Star or Star of Twilight. Venus is also the planet that is closest to the Earth.Distance of Venus with the sun about 108 million kilometers. One year on Venus equal to 225 Earth days. While there one day equal to 243 Earth days. Thus the period of revolution is faster than the rotation period.
Planet Earth. The universe is so vast, the Earth is only a small part of it. If you see this reality, there might be other life in the universe but for the scope of the Solar System is only the earth was believed to have a life that is highly developed. Another Earth like planet, has no light. Earth also has two other planetary satellites such as the natural satellite of Earth's moon, has motion around the Earth with a lap time of 29.5 days. Earth has a rotation period of about 23 hours 56 minutes and has a period of revolution of about 365 days 6 hours.
Mars. The planet Mars is the planet closest to the outer world. At night sometimes we see a "planet" that glow bright red. That's the red planet Mars or. Its name is derived from the name of the Roman god of war. The planet has a diameter of about 6800 km, or about half the diameter of Earth. Mars rotation period is 24 hours 37 minutes and 687 days during its revolution. Mars has two satellites namely Deimos and Phobos, the temperature on Earth.
planet Jupiter. Planet Jupiter is the largest planet in the Solar System. If we imagine Jupiter as a container, it can accommodate as many as 1310 Earth-sized planet. But it is not proportional to the size, Jupiter is just a half times the weight of the Earth. The planet is soft, the surface only in the form of liquid hydrogen and helium gas that enveloped by clouds moving. Another uniqueness owned by Jupiter is the fastest rotation, it only takes 10 hours. While the period of its revolution takes a very long time which is 12 years old.
Saturn. The sixth planet in the solar system has a unique, surrounded by a ring formed from millions of pieces of ice. Saturn's distance to the Sun about 1.4 billion kilometers. The period of revolution of about 30 years, while the rotation period of about 10.5 hours. This planet has a nature like Jupiter, they spin so fast that it is considered as the most windy planet. The wind speed of more than 10 wind speeds Hurricane on Earth.
Planet Uranus. Uranus was discovered by William Herschel in 1782 with the help of a telescope in his back garden in Bath, England. This planet is one of the planet away from the Sun.Consisting of a main gas such as hydrogen, methane and helium as well as gassy. This situation makes Uranus chilled and frozen. Just like Saturn, Uranus also have rings. Uranus rings thin and to date have found nine layers of rings of Uranus. Another great feature that is also owned by the planet, the rotation in the opposite direction of rotation of the Earth to make one side like a top that fall. The period of revolution of Saturn around 84 years and the period of rotation varying from 11 hours. As a result, one side of the planet continue to experience daylight for 42 years while the other side continue to experience a night for 42 years.
Planet Neptune. Conditions in Neptune does not differ much from Uranus, consisting of gas. Neptune size large though not as big as Jupiter. If likened to an empty container, capable of accommodating 60 Neptune-sized planet Earth. One year on Neptune is equal to 165 Earth years while there one day about 16 hours on Earth. Since 1984, experts have suspected that Neptune has a ring.
c) dwarf planet or a dwarf planet (Dwarf Planet). In addition to defining a planet, the IAU resolution that took place in Prague also defines "dwarf planet" or a dwarf planet. Terms of defining "dwarf planet" or a dwarf planet similar to the definition of a planet. The difference is the "dwarf planet" or a dwarf planet instead of objects, and not dominant in its orbit satellites (a celestial body orbiting the planet). Pluto a planet previously entered row in the solar system, changed its status as a "dwarf planet" or a dwarf planet. Along with Pluto as the object that was around Pluto classified as a "dwarf planet" is an asteroid or dwarf planet Ceres, 2003 UB313 (discovered by Mike Brown of the California Institute of Technology under the guise of 'Xena') and Pluto's largest moon called Charon.
d) Asteroid. Asteroids are small, rocky planet (1700 km diameter) with a number of very much. In the solar system there are also thousands of asteroids around the sun. Asteroids whose orbits pass through the Earth's orbit called Apollo asteroids. In addition, many of the asteroids that have been named according to the name of the inventor.
Most of the asteroids are found between the orbits of Mars and Jupiter. This area is known as the Northern Belt (Main Belt).Besides that inhabit the asteroid Main Belt region, there is also a group of asteroids with orbits different as the Trojan asteroids and the AAA (Triple A-Armor Asteroids, Apollo, Alen).
e) Meteor. When we looked for a moment into the clear sky at night, there was light moving quickly and disappear. That meteor. Meteors are also called shooting stars or a separate part of the asteroid.Meteors are falling leading to the Earth will look like a ball of fire.
Meteors are falling very much and sometimes called a meteor shower. When a meteor shower, millions of meteors enter the Earth's atmosphere, but most burn up before they reach the earth's surface. Sometimes meteors are not burned out and eventually came to the earth's surface and is called a meteorite.
Large meteorite that fell to earth would form a large crater as Barringer Crater in Arizona territory. The crater was formed by a meteor that fell about 40,000 years ago.
f) Comets. Comets are celestial bodies visible luminous atom due to friction in the air. Size can exceed 10 miles and has a long tail millions of miles. Therefore, the comet is often called shooting stars.Characteristic of the comet is a very long tail. The length can reach 100 million km. nucleus of a comet is called the nucleus which consists of chunks of ice and frozen gases. Nucleus diameter can reach 10 km. is part of the comet's tail, derived from the coma surrounding the comet's nucleus. Coma diameter can reach 100,000 miles.
One of the famous comet is Halley's comet. The comet was discovered by Edmond Halley. The average period of Halley's comet orbits emergence occurred every 76-79 years. Halley's Comet was last seen in 1986 and is expected to appear back in the year 2061. The core or center of the comet Halley is very dark with a diameter of approximately 1024 km.
In addition to comet Halley comet there are several other names, such as comets Hyakutake and Hale Bopp. The experts said that in 251 million years ago there was a very large extinctions caused comet or asteroid had hit the Earth. The conclusion was obtained from the trapped atoms in the carbon molecular framework. But it is not yet known where the location of the comet or asteroid collision with the earth.
Did you?
Do you know the record holder planet? Venus the hottest planet with a temperature of 462oC, which is the fastest moving planet Mercury with a velocity 172 000 km / hour, the Earth's most tightly-density five times denser than water.
A visitor from Outer Space. Earth since ancient times often visited by visitors from outer space in the form of an asteroid, meteor or comet. Celestial bodies that are believed to create an ecosystem on Earth. Thousands of meteorites bombard Earth every year. Just because the size is very small, this meteor was destroyed by fire when it enters the atmosphere. Some of them may still remain and fell to Earth in the form of a fireball (meteorite). Apda real incident on June 30, 1908, when a mere 60 meters in diameter meteorite exploded at an altitude of 15 kilometers above the Tunguska forest in Siberia. Within a radius of 60 kilometers as the great earthquake rocked. At a radius of about 20 kilometers from the center of the explosion, burning forests and ravaged. In addition, experts estimate the extinction of the dinosaurs 65 million years ago caused the fall of an asteroid 10 kilometers to the Yucatan Peninsula in Mexico.
(Source: Sudibyakto, HA 2009. Geografi.Jakarta: Ministry of Education.)
A) Universe
1) Theory of the Universe
a) The theory of the "Big Bang". One theory to explain the process of the universe is the theory of the "Big Bang". According to this theory, the universe is made up of a powerful explosion that occurred about 13 700 million years ago. The explosion of very large material ejected in all directions of the universe. The material was eventually form stars, planets, cosmic dust, asteroids, meteors, energy, and other particles.
The theory of the "Big Bang" was supported by a U.S. astronomer Edwin Hubble that. Based on observations and research conducted, showing that the universe is not static. The farther the galaxy's distance from Earth, the faster the process of development.The findings were further corroborated by an astro physicist from the United States, Arno Penzias and Robert Wilson in 1965 has measured the radiation phase is in space. The findings are then validated by scientists using NASA instrument called COBE Spacecraft between 1989-1993. Recent studies from the laboratory of CERN (European pour la Recherche Camseil Nuclear or European Council for Nuclear Research), located adjacent to Geneva reaffirms the theory of the "Big Bang". All this confirms that the past never unite heaven and earth before finally separated as they are now.
b) The theory of "objec Fixed". The theory of "steady state" or continuous creation theory states that the universe during berabat always in the same state and hydrogen substances ever created out of nothing. Increasing the number of agents, in this theory requires a very long time is a thousand million years to one atom in a volume of space. This theory was proposed by astronomer Fred Hoyle and some experts astro physics England.
In the theory of "steady state", we have to accept that a new substance is always dicipatakan in the space between galaxies that new galaxies are formed to replace a galaxy away. People agreed that the substance that is the origin of stars and galaxies is hydrogen.
This theory is accepted by some experts skeptical others because it violates one of the basic laws of physics is the law of conservation of matter. Matter can not be created or destroyed but can only be transformed into another substance or a type of energy.
It is not yet determined exactly how the universe was formed. The theory advanced by the experts certainly have their advantages and disadvantages on their own.
2) assumption about the Universe and the Universe
a) the assumption or Egoposentris anthropocentric (human center of the universe). This assumption is begun at the beginning of the human or in the primitive humans who consider that man as the center of the universe. At the time realized there was earth and sky, people assume the sun, moon, stars and Earth are similar to animals, plants, and with himself.
b) The presumption Geosnetris (earth center of the universe). This assumption puts the Earth as the center of the universe. Geocentric (geo = earth; centrum = center point). This assumption started sekitara VI century BC, when the egocentric view of becoming obsolete. One person suggested geocentric assumption is Claudius Ptolemy. He made observations at Alexandria, Egypt cultural center of the city in the past. He considered that the center of the universe is the Earth so that the Earth is surrounded by the sun and stars.
c) The presumption Heliocentric (sun center of the universe). More advanced research tools and the increasingly critical nature of scientists, led to the shifting perception geocentric. The views heliocentric (helios = sun) is considered as a revolutionary who put the sun as the center of the universe.
A student of medicine, science and Astronomy, Nicholas Copernicus (1473-1543) in 1507 wrote the book "De Revolutionibuss orbium Caelestium" (about the circulation of celestial revolutions). He argues that the sun is the center of the universe surrounded by planets, the moon around the Earth and together around the sun, and the Earth perputar eastward causing day and night.
d) The presumption Galaktosentris (galaxy as the center of the universe). Galaktosentris (Galaxy = a collection of millions of stars) is the presumption that places the galaxy at the center of the Solar System. Galaktosentris began in 1920 that was marked by the construction of a giant telescope in the United States, so as to provide more information about the galaxy.
B) Galaxies in the Universe.
1) Definition of the Galaxy. The astronomers concluded that the galaxies are in the universe with billions of galaxies each containing hundreds of billions of stars. To be able to observe the count moreover, would not be seen with the naked eye, need a tool called a telescope.
The galaxy is a star or order sisitem stars. Galaxies gather arranged and each member galaxy has attractive force (gravity).The sun with its planets in a galaxy called the Milky Way.
Including the Milky Way galaxy and a spiral-shaped like a disc, diameter of about 100,000 light years. The term describes light years distance traveled by light in one year. With a speed of 300,000 km / sec, within one year of light will ditempu distance of about 9.5 trillion miles. So, a light year is 9.5 trillion miles. This means the diameter of our galaxy about 100.000X9, 5 trillion km or 950 bilium km (950 followed by 15 zeros behind the fruit). Excellent away is not it? To simplify the calculations we used the light-year distance unit. With this unit, the thick central part of our galaxy about 10,000 light-years away.
So, where is our sun? The sun is located about 30,000 light years from the center of the Milky Way. The sun is not a star special, but just one of 200 billion pieces star member of the Milky Way. Stars Milky Way members are scattered dengna distance from one star to another star ranged from 4 to 10 light years. The more towards the center of the galaxy, interstellar distances closer or in other words, towards the center of the galaxy density increases.
| Galaksi (Galaxy) | Jarak dari Bumi (Tahun Cahaya)/ distance from Earth (light years) |
| Magellan | 180.00 |
| Andromeda (M31) | 2.200.000 |
| M32 | 2.300.000 |
| Triangulum (M33) | 2.400.000 |
| Wolf-Lundmark | 4.290.000 |
| M81 | 9.450.000 |
| Centaurus A | 13.040.000 |
| Pinwheel (M101) | 23.790.000 |
| Whirlpool (M51) | 29.340.000 |
| NGC2841 | 37.490.000 |
| NGC1023 | 39.120.000 |
| NGC3184 | 42.380.000 |
| NGC5866 | 42.380.000 |
| M100 | 48.900.000 |
| NGC6643 | 74.980.000 |
| M77 | 81.500.000 |
| NGC3938 | 94.540.000 |
| NGC2207 | 114.100.000 |
| NCG205 | 2.200.000 |
The total number of galaxies that can be photographed with a diameter of 500 cm telescope at Mount Palomar, the United States, an estimated one billion pieces of galaxies. If using a large telescope of course we can see galaxies far more and with greater distances longer than the galaxy known so far.
2) Shape Galaxies.
According to the morphology of galaxies are divided into three types, namely type spiral galaxies, elliptical and irregular. The division is based on the type or appearance betuk galaxies.Observations astronomers showed that galaxies in the universe are made up 75% of spiral galaxies, 20% and 5% elliptical galaxies, irregular galaxies. However, elliptical galaxies are believed to be the type most numerous galaxies in the universe. If we take the same volume of space, we will find more elliptical galaxies than spiral galaxies. It's just that many galaxies of this type that looks so dim that it was difficult to observe.
a) No irregular galaxy. This galaxy has no particular form. Members of the galaxy is composed of young and old stars. Examples of this type of galaxy is the Large Magellanic Cloud and Small Magellanic Clouds, two neighboring galaxies closest to the Milky Way, which is only about 180,000 light-years from the Milky Way. Irregular galaxy contains a lot of interstellar matter consists of gas and dust.
b) Elliptical Galaxies. Sightings terliaht like elliptical galaxies.Galaxies are included with this type of elliptical galaxies ranging from circular to spherical galaxies pepat. The structure of this type of galaxy is not seen clearly. Elliptical galaxy contains very little interstellar matter and its members are old stars. Examples of this type of galaxy is the galaxy M87, a giant elliptical galaxy that is located in the constellation Virgo.
c) Spiral Galaxies. The main part is a spiral galaxy halo, the galactic plane (including the spiral arms) and the bulge (a prominent part of the galactic center). A spiral galaxy consists of young and old stars.Old stars found in a collection of hundreds of star-shaped ball (spherical clusters). Young stars in the spiral arms of galaxies are located in the galactic plane. Spiral galaxies rotate so fast that makes this galaxy flattened and form the galactic plane. Examples of this type of this type of galaxy is the Andromeda galaxy and the Milky Way. In the Milky Way galaxy is the Earth as part of the Solar system is located.
C) Solar System
1) The theory of the Solar System
a) Theory Nebula (by Immanuel Kant and the Marquis de Laplace).This theory says that family members initially shaped the Solar System raksassa a glowing mass of gas and rotates slowly. This mass gradually cooled, shrink, and approximates the shape of a ball. Rotation mass is higher and higher. As a result, the center of mass of that bubble. Finally loop material thrown out. The circle is cooled, shrink and eventually become planets.
The planet is still orbiting around the center of mass. Then, another circle was thrown away from the center of mass and a whole planet, including Earth. Ultimately all the planets formed. Center of mass to our sun. Furthermore, the planet is also the time threw out the sky and turned into a satellite or moon.
b) planetesimal theory (by Forest Ray Moulton and TC Chamberlain). This theory states that when a star crosses a space quickly and are close to the sun sekli. The star attraction is so great that it caused the gas plug in the hot sun. As a result, the mass of the Sun and the gas was thrown from orbit. Because the sun's appeal, held that the gas mass and moves around the sun. When the mass of the gas to cool, form into a liquid then solidifies. Finally, the mass of the gas into the existing planets, including Earth.
c) Put Theory (by Sir James Jeans and Sir Harold Jeffreys). This theory is also based on the idea of conflict. This theory says that planets are formed directly by the original gas attracted by a star passing nearby. Thus, this theory is almost the same as the theory originally planetesimals. The difference that this theory is not formed by planetesimal planet. According to this theory, when the star is approaching or even grazed the Sun, its gravitational pull suck gas cigar-shaped filament length. Filament enlarged in the middle, narrowed at both ends, these filaments eventually forming a planet.
d) Theory of Lyttleton (by R. A. Lyttleton). This theory says that the Sun first twin stars form around a gravitational field. A star hit one of the twin star and possibly destroy it. Stars who ruined it turned into a rotating mass of gas. Due to continued spinning, gas cools the planet formed.
The stars who survived, became our sun. Because of the strength of gravity, the Sun hold planets formed and circulated by its trajectory now. Thus, it is clear that this theory is also based on the idea of conflict.
c) Dust Cloud theory (Fred L. Whippel). This theory says that the candidate of the Solar System was originally a vast cloud. Clouds composed of dust and gas is expected cosmos is shaped like a plate. Irregularity of the cloud caused the turnaround. Dust and gas rotating gathered into one. While dust and gas it kept spinning, cloud disappears .. harsh dust particles collide with each other, and then attached to the planet. Various gases contained in the clouds develop into the sun.
Theories are just a few of the many theories that have been raised by experts about the Earth. There is no one among these theories are considered completely satisfactory and widely accepted by the whole world. Each of these theories has excess and lack. However, we hrus know that the theory put forward based on research, observation, and calculation. We must respect their thoughts.
2) Members of the Solar System
a) The sun. The sun is the center of the Solar System. Diameter size of the Sun is a hundred times larger than Earth. However, for the size of the universe, including the sun a little star. There is still an amount of one hundred stars from the Sun.
Distance of the Sun to the Earth about 150 million kilometers.Distance of the Sun to the Earth is called the astronomical unit (1 sa). The time taken by the sun to reach the earth 8.33 min.
The sun is made up of core and skin layers. The skin of the Sun consists of layers fotosfera, khromosfera, and corona. Fotosfera gas is emitted in all directions. At the top there is a layer fotosfera khromosfera. Corona is the outermost part of the sun, a flame is lit.
As with other stars, the sun emit energy nuclear reaction proceeds very powerful. Radiant energy yield of nuclear reactions in the core produce heat for 15 million oC. Compare the temperature at the surface only 6,000 oC. It was unbelievably hot. Therefore, in the sun there is no solid objects. Everything is in the form of gas.
b) Planet. Planets are celestial bodies in the solar system moves around the sun in the trajectory (orbit) are stable. It first, we know that nine planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. But now recognized as a member of the solar system planets except Pluto was only eight. Why does this happen?
General Assembly of the International Astronomical Society (International Astronomical Union / IAU) to 26 which took place in Prague, Czech Republic, on August 25, 2006 has decided several important decisions, among them the 5A resolution that contains the definition of a planet. A celestial body can be called a planet if it has the following requirements:
i) Being in an orbit around the sun.
ii) Having sufficient weight to overcome the pressure of gravity itself in rigid so that he became a hydrostatic equilibrium (nearly round shape).
iii) It is the dominant object in its own orbit
Based on the definition of Pluto outcome of the trial (International Astronomical Union) IAU, Pluto does not qualify as a planet because Pluto has an orbit that overlaps with Neptune's. It shows Pluto as an object that is not dominant in its own orbit. Pluto has the status of a planet since it was discovered by Clyde Tombaugh in 1930, eventually losing its status as a planet. Currently recognized as a planet in the Solar system is only eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Mercury. Mercury is the closest planet to the Sun. Proximity is the temperature on Mercury is very hot. Hot day at the Mercury is very high, supposedly able to melt tin cans lining. The distance between the Sun with Mercury approximately 57 million miles. while the distance to the Earth about 92 million miles. size of only 27% of the size of the Earth. Mercury around the Sun (revolution) took 88 days while the rotation takes 59 days. The planet rotates once a symbol that one day is almost the same length with a year on Earth.
Planet Venus. The second nearest planet from the Sun is Venus.One characteristic of the planet is a thick cloud enveloped him. The cloud makes terpantulkan sunlight. As a result, the planet Venus being the brightest. The light will appear when the sun rising and setting. Therefore, inisering planet known as the Morning Star or Star of Twilight. Venus is also the planet that is closest to the Earth.Distance of Venus with the sun about 108 million kilometers. One year on Venus equal to 225 Earth days. While there one day equal to 243 Earth days. Thus the period of revolution is faster than the rotation period.
Planet Earth. The universe is so vast, the Earth is only a small part of it. If you see this reality, there might be other life in the universe but for the scope of the Solar System is only the earth was believed to have a life that is highly developed. Another Earth like planet, has no light. Earth also has two other planetary satellites such as the natural satellite of Earth's moon, has motion around the Earth with a lap time of 29.5 days. Earth has a rotation period of about 23 hours 56 minutes and has a period of revolution of about 365 days 6 hours.
Mars. The planet Mars is the planet closest to the outer world. At night sometimes we see a "planet" that glow bright red. That's the red planet Mars or. Its name is derived from the name of the Roman god of war. The planet has a diameter of about 6800 km, or about half the diameter of Earth. Mars rotation period is 24 hours 37 minutes and 687 days during its revolution. Mars has two satellites namely Deimos and Phobos, the temperature on Earth.
planet Jupiter. Planet Jupiter is the largest planet in the Solar System. If we imagine Jupiter as a container, it can accommodate as many as 1310 Earth-sized planet. But it is not proportional to the size, Jupiter is just a half times the weight of the Earth. The planet is soft, the surface only in the form of liquid hydrogen and helium gas that enveloped by clouds moving. Another uniqueness owned by Jupiter is the fastest rotation, it only takes 10 hours. While the period of its revolution takes a very long time which is 12 years old.
Saturn. The sixth planet in the solar system has a unique, surrounded by a ring formed from millions of pieces of ice. Saturn's distance to the Sun about 1.4 billion kilometers. The period of revolution of about 30 years, while the rotation period of about 10.5 hours. This planet has a nature like Jupiter, they spin so fast that it is considered as the most windy planet. The wind speed of more than 10 wind speeds Hurricane on Earth.
Planet Uranus. Uranus was discovered by William Herschel in 1782 with the help of a telescope in his back garden in Bath, England. This planet is one of the planet away from the Sun.Consisting of a main gas such as hydrogen, methane and helium as well as gassy. This situation makes Uranus chilled and frozen. Just like Saturn, Uranus also have rings. Uranus rings thin and to date have found nine layers of rings of Uranus. Another great feature that is also owned by the planet, the rotation in the opposite direction of rotation of the Earth to make one side like a top that fall. The period of revolution of Saturn around 84 years and the period of rotation varying from 11 hours. As a result, one side of the planet continue to experience daylight for 42 years while the other side continue to experience a night for 42 years.
Planet Neptune. Conditions in Neptune does not differ much from Uranus, consisting of gas. Neptune size large though not as big as Jupiter. If likened to an empty container, capable of accommodating 60 Neptune-sized planet Earth. One year on Neptune is equal to 165 Earth years while there one day about 16 hours on Earth. Since 1984, experts have suspected that Neptune has a ring.
c) dwarf planet or a dwarf planet (Dwarf Planet). In addition to defining a planet, the IAU resolution that took place in Prague also defines "dwarf planet" or a dwarf planet. Terms of defining "dwarf planet" or a dwarf planet similar to the definition of a planet. The difference is the "dwarf planet" or a dwarf planet instead of objects, and not dominant in its orbit satellites (a celestial body orbiting the planet). Pluto a planet previously entered row in the solar system, changed its status as a "dwarf planet" or a dwarf planet. Along with Pluto as the object that was around Pluto classified as a "dwarf planet" is an asteroid or dwarf planet Ceres, 2003 UB313 (discovered by Mike Brown of the California Institute of Technology under the guise of 'Xena') and Pluto's largest moon called Charon.
d) Asteroid. Asteroids are small, rocky planet (1700 km diameter) with a number of very much. In the solar system there are also thousands of asteroids around the sun. Asteroids whose orbits pass through the Earth's orbit called Apollo asteroids. In addition, many of the asteroids that have been named according to the name of the inventor.
Most of the asteroids are found between the orbits of Mars and Jupiter. This area is known as the Northern Belt (Main Belt).Besides that inhabit the asteroid Main Belt region, there is also a group of asteroids with orbits different as the Trojan asteroids and the AAA (Triple A-Armor Asteroids, Apollo, Alen).
e) Meteor. When we looked for a moment into the clear sky at night, there was light moving quickly and disappear. That meteor. Meteors are also called shooting stars or a separate part of the asteroid.Meteors are falling leading to the Earth will look like a ball of fire.
Meteors are falling very much and sometimes called a meteor shower. When a meteor shower, millions of meteors enter the Earth's atmosphere, but most burn up before they reach the earth's surface. Sometimes meteors are not burned out and eventually came to the earth's surface and is called a meteorite.
Large meteorite that fell to earth would form a large crater as Barringer Crater in Arizona territory. The crater was formed by a meteor that fell about 40,000 years ago.
f) Comets. Comets are celestial bodies visible luminous atom due to friction in the air. Size can exceed 10 miles and has a long tail millions of miles. Therefore, the comet is often called shooting stars.Characteristic of the comet is a very long tail. The length can reach 100 million km. nucleus of a comet is called the nucleus which consists of chunks of ice and frozen gases. Nucleus diameter can reach 10 km. is part of the comet's tail, derived from the coma surrounding the comet's nucleus. Coma diameter can reach 100,000 miles.
One of the famous comet is Halley's comet. The comet was discovered by Edmond Halley. The average period of Halley's comet orbits emergence occurred every 76-79 years. Halley's Comet was last seen in 1986 and is expected to appear back in the year 2061. The core or center of the comet Halley is very dark with a diameter of approximately 1024 km.
In addition to comet Halley comet there are several other names, such as comets Hyakutake and Hale Bopp. The experts said that in 251 million years ago there was a very large extinctions caused comet or asteroid had hit the Earth. The conclusion was obtained from the trapped atoms in the carbon molecular framework. But it is not yet known where the location of the comet or asteroid collision with the earth.
Did you?
Do you know the record holder planet? Venus the hottest planet with a temperature of 462oC, which is the fastest moving planet Mercury with a velocity 172 000 km / hour, the Earth's most tightly-density five times denser than water.
A visitor from Outer Space. Earth since ancient times often visited by visitors from outer space in the form of an asteroid, meteor or comet. Celestial bodies that are believed to create an ecosystem on Earth. Thousands of meteorites bombard Earth every year. Just because the size is very small, this meteor was destroyed by fire when it enters the atmosphere. Some of them may still remain and fell to Earth in the form of a fireball (meteorite). Apda real incident on June 30, 1908, when a mere 60 meters in diameter meteorite exploded at an altitude of 15 kilometers above the Tunguska forest in Siberia. Within a radius of 60 kilometers as the great earthquake rocked. At a radius of about 20 kilometers from the center of the explosion, burning forests and ravaged. In addition, experts estimate the extinction of the dinosaurs 65 million years ago caused the fall of an asteroid 10 kilometers to the Yucatan Peninsula in Mexico.
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