Crash Course Astronomy: Asteroids

For this week's Crash Course Astronomy episode, we take a skidding halt at the edge of the planetary solar system and scream back inward to the vast space between Mars and Jupiter. Before I go on, I need to fess up to an error: I said that Earth's Trojan asteroid, 2010 TK7, is 800 million km from Earth. I have no idea how I came up with that number; when it's 60° ahead it's about 150 million km ahead of us, and it wanders around to almost opposite the Sun from us, when it's roughly 450 million ...