Recently you may have noticed a couple things: 1) COSI is getting a whole bunch of dinosaurs, and 2) I'm kind of excited by it. Growing up I read - or more accurately, consumed - two kinds of books: books about space and books about dinosaurs. There was also an 80's cartoon series that featured dinosaurs from space, which while pretty awesome didn't offer much educational value. So you can imagine my delight when I learned that a rock from space was responsible for killing almost all the dinosaurs about 65 million years ago. Don't get me wrong - I felt bad for the dinosaurs, but I was happy to learn that my two passions were strangely connected. In fact it was a physicist and a geologist that first identified this cataclysm. Buried within strata all across the globe is a thin line of dark earth with an usually large concentration of iridium. Iridium is pretty heavy and pretty rare, since most of it sunk to the Earth's core billions of years ago before the planet chilled out from its molten state. But it's still found in abundance in any remnant from the days of the early solar system. Say, asteroids. That dark line is about 65 million years old, and there are plenty of dinosaurs below it and not so many above it. Ergo: extinction event. And the size of that dino-killer rock from space? A mere six miles across.