Astropark Home . Solar System . ... Planets . ... A year is the time that it takes for a planet to go around the Sun. ... As a result, an Earth year is very different in length from a year on Saturn or any other planet. ... But on this scale, most of the planets are too small to see, so their size has been increased by 200 times. ... The Astropark's red gravel represents the asteroid belt – thousands of smaller bodies which range in size from pebbles up to small planets hundreds of miles across. ...