The number of years a radio signal would take to reach the Andromeda galaxy. - How many years would a radio signal take to reach the nearest large galaxy to us, the Andromeda galaxy? (Hint: Consider the nature of all electromagnetic waves.)

Compare the stars found in the galactic disk - Compare the stars found in the galactic disk (where the sun is located), also known as Population I stars, with the stars in the halo of our galaxy, known as Population II stars. **** Minimum 100 words - Cite all sources / urls

Describe the nature of the material between the stars, and how is it observed? - Describe the nature of the material between the stars, and how is it observed? **** Minimum 100 words - Cite all sources / urls *******

The study of the most distant galaxies in comparison to ours. - Why is the study of the most distant galaxies we can see related to the study of conditions around the time that our galaxy (and perhaps others) was forming?

How are planets detected around other stars? - How are planets detected around other stars? **** Minimum 100 words - Cite all sources / urls