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The Solar System

The group of planets, moons, and space debris orbiting around our Sun.

It was probably formed from a huge cloud of interstellar gas and dust that contracted under the force of its own gravity five billion years ago.

Our Home

The solar system is the planetary system in which we live.

It is held together by the gravitational pull of the Sun, which is nearly 1,000 times more massive than all the planets put together.

The Inner Planets

The planets are divided into two groups.

The four planets closest to the Sun are called "terrestrial," from the Latin word terra, meaning "land," because they are small and dense and have hard surfaces.

Between Mars and Jupiter there is a belt of very small bodies called the asteroid belt.

The Outer Planets

The four outer planets are called "Jovian" because, like Jupiter, they are giant planets made largely of gas and liquid.

Beyond Neptune there is a belt of very small bodies and dwarf planets called the Kuiper belt.