(a) How long does it take a radio signal to travel 150 km from a transmitter to a receiving antenna?

(b) We see a full Moon by reflected sunlight how much earlier did the light that enters our eye leave the Sun? The Earth-Moon and Earth-Sun distances are 3.8 x 105 km and 1.5 x 108 km, respectively.

(c) What is the round-trip travel time for light between Earth and a spaceship orbiting Saturn, 1.3 x 109 km distant?

(d) The Crab nebula, which is about 6500 light-years (l y) distant, is thought to be the result of a supernova explosion recorded by Chinese astronomers in A.D. 1054. In approximately what year did the explosion actually occur?