Answer questions like ...

1. Earth and Venus are rocky planets of about the same size, but Earth's average surface temperature is about 59° F, while Venus' is 1,350° F, hot enough to melt lead or aluminum. Why the difference?
2. Earth is smack in the middle of the "habitable zone" around the sun, where temperatures are right for liquid water to exist.
3. Earth is the only body in the solar system thought to have oceans of liquid water.

Use the green Start Show button above to start playing!