Asteroids! No not the video game - I'm talking about all those old rocks floating around up in space. Here's an incredible video tracking every single one of them that's visited our solar system since 1980. Space: busy place!
The video's description notes:
As the video moves into the mid 1990's we see much higher discovery rates as automated sky scanning systems come online. Most of the surveys are imaging the sky directly opposite the sun and you'll see a region of high discovery rates aligned in this manner.
So basically space is an even busier place than this video shows - it's just that before 15 or so years ago we were too unintelligent a life form to know it. [Gawker]