Surface

"Don't go around saying the world owes you a living. The world owes you nothing. It was here first." -Mark Twain So, you've been around a while, seen all sorts of things, and learned an awful lot about the world, solar system and Universe that we live in. But how well do you know it, really? Image credit: NASA / Lunar and Planetary Laboratory. To scale and in order, these are the eight planets you know so well. There are the four rocky worlds of our inner solar system: Mercury, Venus, Earth, and Mars, and the four gas giants that dominate the outer solar system: Jupiter, Saturn, Uranus, and…