Question-

1. What is the primary source of light pollution?

2. Why are reflector telescopes generally superior to refractor telescopes?

3. What space probes have visited the planet Mercury? Which one is still actively studying the planet?

4. What are the hydrogen alpha and hydrogen beta lines? What kinds of spectra demonstrate these lines?

5. Originally the planetary interiors were heated by gravitational energy from in-falling objects and the sinking of denser materials toward the core. Presently the interior of the terrestrial planets are too hot for the current hear to be produced by left over gravitational energy. What is the current source of heat for the interior of terrestrial planets?