I like astronomy  and I want recommend one Internet service.It was create by John Worth. The service shows our solar System in a real scale.Most of the square space is emptiness.The  service supports Ukrainian and Russian languages.You can assess the distance in different units of length, for example, in length of Great Walls of China or blue whales.You can visit the service by the link:http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html.