Guiding Questions

• How did ancient astronomers explain the motions of the planets?

• Why did Copernicus think that the Earth and the other planets go around the Sun?

• How did Tycho Brahe attempt to test the ideas of Copernicus?

• What paths do the planets follow as they move around the Sun?

• What did Galileo see in his telescope that confirmed that the planets orbit the Sun?

• What fundamental laws of nature explain the motions of objects on Earth as well as the motions of the planets?

• Why don’t the planets fall into the Sun?

• What keeps the same face of the Moon always pointed toward the Earth ?