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The milky way galaxy, home to our solar system. It's believed that our solar system was formed at least four and half billion years ago, when a huge cloud of dusty gas collapsed into a dense mass. That mass began to spin and flattened into a disk. The center grew harder and harder until finally, a new star, our sun was born. Leftover dusty gases continue to whirl around the sun and over millions of years formed the plants and moons that make up our solar system. The Sun is at the center, its gravity binds the solar system together. It counts for 99% of the solar system's mass. The closest plant to the sun is Mercury, a relatively small planet known for its extremes of temperatures. Above 100 degrees Fahrenheit during the day and minus 300 and so degrees at night. Next is Venus, the near twin of the Earth,in size, mass, and density. Its atmosphere is mostly carbon dioxide, a green house gas that traps the Sun's heat and raises the surface temperature to nearly 900 degrees Fahrenheit. Clouds so filled of gases swirl of Venus' rocky surface. The third planet is Earth, an active planet that is constantly changing. More than 70% of its surface is covered by water. Earth teems with life, something that so far has been found nowhere else. Just beyond the earth lies Mars, a barren planet with striking geographic features, including red soil, canyons four times deeper than the Grant Canyon, and polar ice. Between Mars and next planet is the Asteroid Belt, a millions of rocky fragments, most no more than a mile across. The 5th planet from the Sun is far away the largest, Jupiter, a gassy giant, big enough to hold more than 13,000 earths. Its great red spot alone, a huge hurricane like storm, is twice as wide as earth. Saturn, the 2nd largest planet is next, famous for its massive rings of ice and ice covered particles. Seventh from the sun is Uranus, which is unique because it rotates on its side. It, too, has rings, and at least 27 moons. Neptune, the 8th planet, is perhaps the windiest place in the solar system, with gust over 1200 miles per hour. Neptune marks the end of the planets, but not the end of the solar system. Farther on is Pluto, a dwarf planet. At its great distance, Pluto orbits more than 4.5 billion miles from the Sun. As vast and diverse as our solar system is, it's but one of the galaxies of billions of stars in a universe comprised of galaxies.
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