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The Solar System

The Solar System consists of one star (the Sun), nine planets and their satellites, comets, and thousands of minor planets called asteroids. The order of thhe planets from the Sun are as follows: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Most of the asteroids that litter the Solar System lie in a belt between the orbits of Mars and Jupiter. It is believed that most of the comets we see come from a cloud of comets surrounding the Solar System far beyond the orbit of Pluto. This is called the Oort cloud of comets. Every now and then, when the gravity of the Sun pulls one of the comets it, it puts on a show for us Earthlings.

The Sun contains 99.85% of all the mass in the Solar System, with most of the rest being held by Jupiter. The planets combined contain 0.135% of the matter, with the satellites of the planets, comets, and asteroids making up the rest. The four innermost planets, Mercury, Venus, Earth, and Mars, are called the terrestrial planets. They all have a surface of rocky material and a significant atmosphere, except for Mercury. Jupiter, Saturn, Uranus, and Neptune are the Jovian "gas giants". They are made almost entirely of gas, although some, if not all, have a solid core. Last is little Pluto, the farthest planet in the Solar System.

The Solar System Table of Contents

Part I
The Sun
Part II
Part III
Part IV
Part V
The Moon
Part VI
Part VII
Part IIX
Part IX
Part X
Part XI
Part XII
Asteroids and Comets

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