Solar System Facts

Solar System Facts
The solar system encompasses the sun, the eight planets, dwarf planets and smaller objects orbiting the sun as well as the moons that orbit the planets. The solar system formed about 4.6 billion years ago when a giant molecular cloud suffered a gravitational collapsed. People originally believed that the earth was the center of the universe and did not recognize the solar system's existence. Nicolaus Copernicus was the first to suggest that the sun was the center of the solar system and not the earth. The telescope's invention led to the discovery of planets and moons that could not be seen with the naked eye.
Interesting Solar System Facts:
99.86% of the solar system's mass is contained within the sun while the remaining mass is made up of the eight planets.
Of the solar system's eight planets, Mercury, Venus, Earth and Mars are the four planets are made of rock and metal.
Jupiter, Saturn, Uranus and Neptune are made up of mostly hydrogen and helium and are considered to be gas giants.
The sun is the solar system's star.
The rock planets are the four closest to the sun and the gas planets are the four farthest from the sun.
Nobody knows for sure how many dwarf planets exist in our solar system. Some of the known dwarf planets are Ceres, Pluto, Haumea, Eris and Makemake.
Within our solar system are asteroids, which are minor planets circling the sun in an asteroid belt.
Comets in our solar system are made up of rock and ice and are sometimes referred to as dirty snowballs.
The distance from the sun to the earth is one astronomical unit.
The solar system will stay as it is today until the sun's hydrogen is all used up in about 5 billion years.
The part of the solar system classified as the inner solar system contains the terrestrial planets and asteroids.
The four rocky terrestrial planets have few or no moons. Mercury has none. Venus has none. Earth has one. Mars has two small moons (AKA satellites).
In the asteroid belt, between Mars and Jupiter, there are small solar system bodies called asteroids. Some of these have moons.
The outer planets in the solar system, also known as gas giants, have more moons than the inner planets. Jupiter has 67 known moons. Saturn has 62 known moons. Uranus has 27 known moons. Neptune has 14 known moons.
The area in the solar system beyond Neptune has not been explored much and is known as the ‘trans-Neptunian region'.
When Pluto was discovered in 1930 it was classified as a planet, making it the ninth planet in the solar system. However when the formal definition of a planet was established, Pluto was reclassified as a dwarf planet.
In 2012 NASAs Voyager 1 is believed to have reached the transition zone leading to the solar system's outer limit.
The solar system exists within the Milky Way. The Milky Way is a spiral galaxy with about 200 billion stars and a diameter of 100,000 light years.

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