There is only one correct answer to each question. Suppose each star that has planets has10 planets. Put the following objects and lengths in the Universe in order of increasing size in the spaces provided below. There is a bowl diagram on the facing page. The horizon, sky, observer, and the North compass point are already drawn for your convenience.
Radio waves are a form of light and travel at the speed of light.
Suppose astronauts have established a base on Pluto. After 6 hours, Mission Control still has not received a radio reply to their question from Pluto. Mission Control should not worry. The diameter of Pluto's orbit around the Sun is 10 light hours. So roughly speaking, Earth is about half that distance from Pluto or 5 light hours.