You probably know most about Earth then any of the other planets, because you live on it. Earth is different from all the other planets in the solar system. Earth has liquid water on it, and supports life. Scientists haven't discovered liquid water or life on any other planets in the solar system. The earth has two different kinds of life on it--animal and plant. On earth, for there to be animal life, there must be plants. And for plants to live there must also be animals. Without plants and animals, earth would be hot and airless like Venus.
Earth Fact Sheet