How scientists determine the internal structure of the Earth.

How can scientists determine the internal structure of the Earth, if the depth of the deepest well is only a tiny fraction of the Earth's diameter?

cratering, volcanism

3. Impact cratering, volcanism, tectonics, and erosion are the four major processes that affect planetary surfaces. Briefly explain any two. (Please provide all references and complete Urls)

The ages of the Earth and Moon.

If the ages of the Earth and Moon are nearly identical, as believed, why are most rocks found on the Moon so much older than Earth rocks?

The origin of the Moon.

What do observations of the Moon suggest about its origin?

The differences between Earth's and Venus' atmospheres.

Venus and Earth are about the same size and mass, yet carbon dioxide is a major constituent of the atmosphere of Venus, while oxygen is much more abundant in the Earth's atmosphere. Explain why the atmospheres are so different.