What do you suppose it is made of?
What other information do we have?
Model for the structure of the Earth.
Another piece of information: the Earth has a magnetic field
What does the continental crust do?
How old is the Earth?
What is the Earth's atmosphere made of?
What about the weather?
Why is the temperature nice?
Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA email@example.com