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The Terrrestrial Planets are the closest to the Sun and are commonly made of rock and metals. Earth is a special example of a terrestrial planet becasue of its position around the sun. It is not so close that water on the surface is a gas and not so far away that the water is a solid. Life was able to evolve on Earth becasue of this crucial positioning.
Venus and mars are prime examples of what happens when a planet is to close or too far away from its star. Both mars and venus used to have liquid water on their surfaces. Venus was too close to the sun and the water evaporated and helped contribute to the planet's global warming and heavy atmosphere. The atmosphere on Venus is heavy enough to crush a car. Mars on the otherhand, was too far away from the sun and its core cooled and stoped spinning, causing its magnetic field to dissolve. Its water was blasted off the surface by the Sun's solar wind, leaving a barron surface.
Murcury is the closest planet to the sun and therefore has the shortest orbit. Murcury orbits around the sun every 88 days, which is much shorter than an orbit of the Earth, which is about 365 days.
The Gaseous Planets are beyond the frost line, where liquid water changes to ice. These planets are known for there size, which can be attributed to their position in the Solar System. When the Sun ignited, it pushed tons of gas and dust into the outer reaches of the Solar System where the Gaseous planets would form. These planets started out as a small rocky world like the Terrestrial planets, but they grew larger until their gravity began pulling in the gas around them. Jupiter was the first to form and had the most gas to feed on and therefore is the largest of the planets.
Satern's famous rings are really made of small pieces of rock, ice, dust that range from a number of feet to miles across. They are grouped into layers going outward from the planet and are constantly changing. If you can believe it, when Saturn first formed it had no rings. They were created when a large moon came to close to the planet and was ripped apart by its intense gravity. Another moon outside the rings is resupplying the rings with new material when it jets out water from cracks in its surface.
Pluto, the smallest planet in the Solar System was demoted form planet status when astronomers discovered other objects the same size as Pluto orbiting just beyond the edge of the then known Solar System. They called this place in the Solar System the Kupier belt and because astronomers didn't want to include all these new discoveries as planets, they called them Dwarf Planets, and changed Pluto's title to match that. Most of the objects in the Kuiper belt are made of solid methane, ammonia, and water, which is different than asteroids of rock and metal.