Astronomy_ntj

The Big Bang The most popular theory of creation is the theory of the big bang, a large explosion out of a tiny space. In this explosion 15 billion years ago, all the matter was packed into a space smaller than an atomic nucleus. In a fraction of a second, the universe was the size of earth. It was made up of matter, antimatter and energy. Over the next 300,000 years, the universe expands and cools down. Eventually electrons can start orbiting nuclei without being ripped apart. Hydrogen and helium are formed. Energy starts traveling long distances unimpeded by the electrons. Clumps start forming, starting a period of galaxy building.  The Galaxies

Galaxies, some of the largest structures in our universe, were formed slowly, but in bunches. They were pulled together where there was unevenness in the distribution of matter by gravity. This huge sphere of gas formed many stars as it turned into a galaxy. These stars rotate around the center of the galaxy. In the beginning, galaxies crashed into each other with regularity, but the universe is more spread out now. Though they did form slowly, these galaxies are large clusters of 10 billion stars. 

Our Galaxy The Milky Way galaxy, known to us on Earth as a band of stars, is a large galaxy with 10 billion stars. Our own galaxy, the Milky Way galaxy is full of many stars and opaque gas. When looked at head-on, it is a disk, with stars sandwiching the gas. A large central bulge is 10 times wider than the rest of the galaxy. Halfway out in the disk is our own sun and us. Our galaxy, a spiral galaxy, is the band of stars in the sky for us, is a large, thin galaxy.

The Rotation of our Galaxy The Milky Way galaxy rotates around a central bulge. A massive thing, the central bulge draws everything in with gravity, but they orbit because they are moving. The gas and matter out in space rotates counter clockwise, while the stars rotate clockwise. This makes it appear as if the spiral arms are going counter clockwise. <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%; margin: 0in 0in 10pt;">The orbiting matter picks stars up as it rotates, then drops them back down. This creates the image of the arms going counter clockwise, because the matter is doing that. <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%; margin: 0in 0in 10pt;">Though the Milky Way galaxy rotates, it doesn’t all rotate the way it looks like it is rotating. <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;"> <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">Formation of the planets <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">The planets of our solar system were formed bit by bit. After our star formed out of interstellar gas and dust, the planetesimals were formed. When these <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">rocks collided slowly enough, they combined. But when they didn’t, they shattered into pieces. While this was happening, farther out in the galaxy the gas <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">giants were forming. Jupiter, Saturn, Uranus and Neptune were formed out of gas. The largest planets, they were also our solar system’s first planets. After <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">they had formed, enough plantesimals had formed to make the terrestrial planets. Mars, Venus, Mercury and Earth, these rocky planets were smaller than the <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">giants. Metal sank to the middle of these planets, giving them a core. After this, the planets were in the same shape seen today. <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">

<span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">Formation of Moons, Rings and Comets <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">In a pattern seen throughout the universe, many things rotate around planets. Moons were formed. When plantesimals were drawn in by gravity and started <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">orbiting planets, they created moons. In the case of the terrestrial planets, planetesimals would crash into the planets and send up matter that would orbit <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">the planet. This happened with our planet. Rings were created when plantesimals were torn apart and still orbited planets. Icy planetesimals formed the <span style="color: #0592ff; font-family: 'Times New Roman',Times,serif; font-size: 120%;">comets. All of these things rotated around planets.

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