Discussion Questions: Hubble's Expanding Universe

What is the relationship between a Cepheid star's luminosity, its apparent brightness, and its period? How did these stars help Hubble learn about the size of universe?
What evidence is there that the universe is expanding?
How did Hubble deduce that some galaxies are moving away from our galaxy and some are moving toward it?
How do engineers help astronomers learn more about space?
Why was the Hubble telescope taken into space rather than being used on Earth?