The distance to the North Star, Polaris, is approximately 6.44 1018 m.
(a) If Polaris were to burn out today, how many years from now would we see it disappear?
(b) What time interval is required for sunlight to reach the Earth? (The average Earth-Sun distance is 1.50 1011 m.)
(c) What time interval is required for a microwave signal to travel from the Earth to the Moon and back? (The average Earth-Moon distance is 3.84 108 m.)