The mean distance of Mars from the Earth is 0.5 AU and its orbital period is 687 days. Calculate the orbital period of Jupiter given that its mean distance from the Earth is 4 AU.
Explain the meaning of a degenerate gas. A white dwarf star has a mass of 1030kg. Its luminosity is 1024 Js^−1. Calculate how long it can survive with its present luminosity if its internal temperature is 107K.
If the temperature of the background radiation today is 3 K, at what time after the birth of
the universe was the temperature 1015 K. Take the age of the universe as 15×109
years.