See also: Luna

What is a planet?

A planet is a body with an axis, large enough diameter. It also has to have an orbit the same shape as the other planets. Recently the term dwarf planet is used to describe bodies like Eris and Pluto.

What are the planets?

The terrestrial planets are Mercury, Venus, Earth, and Mars. Mercury is distant and the closest planet to the sun. Venus is the hottest planet because of the greenhouse effect. Earth's position is perfect for life and plants to grow. Mars might have once had life on it. It looks red. It has lots of volcanoes.

The gas giants are too cold and have too much gas to have life. They are Jupiter, Saturn, Uranus, and Neptune.

What is a moon?

A moon is an object too small and gravity forces them to orbit a planet.

What are the moons?

Luna is Earth's moon. Also there is Europa, a cold world. Titan, a world under a thick layer of an atmosphere. There are lots of other moons in our Solar System.

What is an extra - solar planet?

A planet which orbits another star in another solar system.