Astr 104, Spring 2008 – Quiz 1

1. What is the altitude of an object in the sky?
a. The vertical angle at which it is located above the horizon.
b. Its horizontal direction, measured clockwise from due North.
c. Its height in degrees above or below the Celestial Equator.
d. The elevation above sea level you have to be at to see the object.

2. Why is the sky blue during the day?
a. Because we are facing a part of space that is bluer than the rest.
b. Because blue sunlight is scattered around us by the Earth's atmosphere.
c. Because the Earth's surface is warmer than at night and it emits blue light.
d. Because the Sun lights up all of space and we can see much further than at night.

3. Approximately how many stars can we see with the naked eye, in very good viewing conditions?
a. A few hundred.
b. A few thousands.
c. About 1 million.
d. About 100 billion.

4. Why do stars move across the sky overhead throughout the night?
a. Because the stars revolve around the Earth.
b. Because the Earth revolves around the stars.
c. Because the stars rotate around their axis.
d. Because the Earth rotates around its axis.

5. What is the difference between a star of magnitude 1 and one of magnitude 5?