Wednesday, 12 August 2009

Planetary Collision Detected

NASA's Spitzer Space Telescope has uncovered evidence of two planets (or similar-sized celestial bodies) colliding in the recent past, i.e. within the last few thousand years. Spitzer sees infrared light and so was able to detect the signatures of molten rock and debris from the collision. The two planets appear to be smaller than Earth, about the size of our moon and Mercury. I'm a big fan of CGI animations showing physically accurate mayhem in space so I quite like this video that depicts the collision. The animation is somewhat slower than real-time but probably not a great deal - it's pretty close to how you'd see it from a spaceship. Notice how the outer layer of the larger planet is blasted away and the smaller body merges with the larger one, creating a new hot planet.

It's thought that at least two similar collisions happened in the early days of our solar system. One collision stripped Mercury of its mantle, and another collision created a ring of debris around the Earth which eventually became our Moon.

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