Why is there life on Earth but not on any other planet?

Here are some facts about life on Earth that we have discovered today!

-Water contains oxygen which we need for life
-Trees make oxygen
-Earth has just the right temperature for life- thanks to our atmosphere!
-Gravity keeps our atmosphere in place
-The sun's gravity keeps us in orbit and we are a perfect distance away from it.
-Light helps us live by allowing plants to grow to give us food and oxygen.
-Mars and Mercury are too small to keep an atmosphere.
-Most creatures on Earth need oxygen.
-Plants need carbon dioxide.
-We need water to survive because our bodies need it. Plants need it too. It is the most important thing for life!
-There is only a small amount of carbon dioxide in our atmosphere.
-The atmosphere is like a big blanket of insulation
-If we can find water on Mars the possibility of life existing there would be better.
-Without energy virtually nothing would happen.

Do you have any other facts or information that we could add to our list?
Tomorrow we'll be writing an explanation about why there is life here on Earth but not on any other planets.