Astronomy_ido

From Big Bang to galaxies Our universe began about fifteen billion years ago exploding out of nothing. The first hints of structure in the Universe were reflected as minute ripples. Two million years after the Big Bang, Galaxies start to form. Galaxies were classified as one of three things: elliptical, spiral, and irregular. When the Universe was expanding, galaxies were much closer and collided and merged with each other very commonly. In the future it has been predicted that there is a possibility that our galaxy and the Andromeda galaxy may collide. [] Formation of Galaxies In a brief flash, the universe was thought to have inflated from the size of an atom to the size of the Earth. The Galaxy started off as lots of quarks, antiquarks, and energy. Matter and antimatter particles were created from radiation and then were annihilated into energy again. As temperature fell, annihilation overtook particle creation. The galaxy grew at a rapid rate starting from the size of one atom becoming large enough to hold millions of stars. [] Structure of the Galaxies The Milky Way is a huge band of stars that stretches around the Galaxy. The Galaxy is a flat disc of stars that stretches to about 100,000 light years across. In the middle of the Galaxy, there is a central bulge that is 20,000 light years thick. It is predicted that in the central bulge of the galaxy lies a huge black hole. Within the disc lies the Sun on one side of the central bulge; on the opposite side of the central bulge lies a dwarf galaxy which is merging with the Milky Way. Rotation of the Galaxies Our galaxy when seen from the top has four rings wrapped around it which spiral around the central bulge. Each star and gas cloud has its own orbit; the galaxy turns but not like a ridged disc. The sun takes 251 million years to go around the spiral one time and travels at 250 kilometers per second. The spiral arms are where matter temporarily piles up not permanent structures turning with the galaxy. Outside the galaxy is an invisible corona containing ten times more material than seen. The gravity of this matter is pulling on the stars that we see but it is unknown to mankind what it is.

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Formation of the planets Planets made up from disks. Particles accumulate together and pack into larger plumps. Space rocks collide with each other which causes them to either explode or merge together. Eventually, the rocks hit together so much that they form planets. The largest planets are Jupiter, Saturn, Uranus, and Neptune. The smaller planets are Earth, Mercury, Venus, and Mars. These planets were all formed by bunches of rocks colliding with each other over a long period of time.

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Formation of moons and comets Many particles fly through space some hitting others. When this collision occurs, the rocks that are formed can be pulled into orbit with a planet. This then becomes a moon and will move in orbit around the planet. Comets form the same way and when they enter the atmosphere of a planet, they can collide with other rocks or planets. In all, moons and comets are formed by the same source even though they function differently in space.

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