There are nine planets, plus moons, asteroids and comets, orbiting the Sun. All the orbiting objects make up only 1% of the material in the solar system: the Sun accounts for the other 99%. If the Sun were the size of a beach ball (75 cm), Mercury would lie about 30 m and Pluto about 3 km away. The Earth would be 78 m from the ball.

A planet is any of the nine major celestial bodies (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto) that orbit the sun and shine by reflecting its light. Smaller bodies that also have the sun as their primary (that is, are not satellites of a planet) are called asteroids or planetoids.

The solar system consists of the Sun; the nine planets, sixty eight (68) satellites of the planets, a large number of small bodies (the comets and asteroids), and the interplanetary medium.

Nine planets have been discovered in our solar system. Mercury, Venus, Earth, and Mars are the planets closest to the Sun. They are called the inner planets. The inner planets are made up mostly of rock.

The outer planets are Jupiter, Saturn, Uranus, Neptune, and Pluto. Jupiter, Saturn, Uranus, and Neptune are large balls of gases with rings around them. Pluto is the farthest planet from the Sun. It is coated with ice.