Awal Jagat Raya (teori Big Bang)
Ceritanya nih, 15 juta tahun lalu, jagat raya meledak - jadi berantakan akibat "Big Bang". Dalam tempo yang singkat,hanya ada energi yang eksis, energi ini berbentuk energi kalor yang puaaaaaaannnnaaaassss! banget..dari hasil ledakan 1 x 10 dipangkat 32, melebur apa aja yang ada di jagat raya. Sejak itu,materi,energi dan waktu dengan sendirinya terbentuk (susah kan ngebayanginnnya, ibu aja sampe sekarang masih bingung ngebayanginnya). Dalam satu detik pertama, jagat raya yang pertama berekspansi terus menjadi dingin sampai 100 milyar derajat, terus proton,neutron, dan elektron mulai terbentuk.Ngga berapa lama,bersamaan dengan turunnya suhu jagat menjadi 1 milyar derajat di bawah nol, atom nuklei yang kecil mulai terbentuk bersamaan interaksi antara proton dan neutron. Setelah 300.000 tahun, suhu jagat raya turun menjadi 3000 derajat dan atom2 netral membentuk elektron2 yang bergabung dengan atom2 nuklei.
Gravity and the other fundamental forces were also created in this explosion and they began to cause the early atoms to pull together into dense clouds called nebulae. Over time, nebulae collapsed into massive objects called stars, which bathed the universe in light. As the tremendous pressure of a star's own gravity squeezes the atoms inside of it together, stars fuse light elements (such as hydrogen and helium) into heavier ones (carbon, nitrogen, oxygen, etc.) (see our Nuclear Chemistry module for more information). Over billions of years, a star eventually exhausts its nuclear fuel and ends its life in a cataclysmic explosion, called a supernova. This process spreads the star's matter back into space and begins the cycle anew.
As the early universe developed, the stars were drawn together into large clusters called galaxies. One such cluster, called the Milky Way galaxy, began to form approximately 10 billion years ago. Much like other galaxies around it, the Milky Way contains some 100 billion stars spiraling around its center. Then, approximately 5 billion years ago, a new star called the sun was born in this galaxy.In its early years, the sun drew in gas and dust from nearby space. Some of this material began to spin around the early sun, forming a circling disc. Over time, dust and gases in this disc began to clump together into larger objects that eventually formed planets circling around the sun.
Nine planets were born in this solar system, each at a different distance from the sun and with different characteristics. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto each circle the sun in distinct orbits, as the following link clarifies.(http://web.visionlearning.com/custom/astronomy/custom/ASTR1.1-pg-planets2.shtml)
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