AST 248: The Search for Life in the Universe

1. Define the two main premises on which the ancients based their belief in extraterrestrial intelligent life.

   The math in these problems are very straightforward. If you find you are spending a lot of time figuring it out, please see me or the TA for help.

2. In one hour, how many kilowatt-hours (kwh) of energy does the Sun radiate?
   1. This amount of energy is equivalent to how many megatons of TNT?
   2. This amount of energy is equivalent to how many times the world's energy consumption in one hour?
3. Suppose a star is 8 pc away.
   1. How many light-years is that?
   2. How many miles is that?
   3. What parallax angle, in seconds of arc, does this star have?
   4. How long does it take light (or, equivalently, a radio message) to travel from the Earth to the star?
4. How many times more massive is the Sun compared to the Earth?
5. How many times farther is 1 light-year than 1 AU (astronomical unit)?
6. How long does it take light to travel from the Sun to the Earth?