Astr 104, Spring 2008 – Quiz 9

1. What is a galaxy?
a. A cloud of interstellar gas and dust at least 10 light years across.
b. A cluster of stars which contains more than 100 stars.
c. A star, together with all of its planets and surrounding matter disk.
d. A collection of millions or billions of stars bound together by gravity.

2. Are the stars you see in the sky at night with the naked eye inside our own galaxy?
a. Yes, all of them are inside our galaxy.
b. No, each of those stars is inside its own galaxy.
c. A few of them are, but most belong to different galaxies.
d. No, those stars are not inside the galaxy, they orbit around it.

3. How can we find the distance to a nearby galaxy, like Andromeda?
a. We use the parallax method.
b. We find its temperature and use the HR diagram.
c. We look for variable stars such as Cepheids in it.
d. We find its velocity and use Hubble's law.

4. Our galaxy, the Andromeda galaxy, and their satellites together form
a. The Local Group.
b. The Virgo Cluster.
c. The Great Attractor.
d. The Small Magellanic Cloud.

5. What is the name of the galaxy we are in, and what type of galaxy is it?