* Astronomy

On Feb. 28, sky-watchers at the Siding Spring Observatory in Australia sighted an unexpected guest: an asteroid heading directly toward the Earth. From the uncharted reaches of space, the asteroid zoomed toward the planet at 12 miles per second, forcing physicists to scramble for their calculators and crunch the numbers. Within minutes, the astronomers calculated the asteroid's size, mass, speed and vector.
At approximately 69 ft. to 154 ft. in diameter, Asteroid 2009 DD45 posed a serious threat to the planet, and despite global surveillance, no one saw it coming. A similar asteroid destroyed 800 square miles of Siberian forest in the early twentieth century.

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On March 2, an asteroid whizzed past the Earth at a distance of just 41,000 miles -- a near miss by cosmic standards (most communications satellites orbit at a distance of about 22,300 miles from Earth). Headlines around the world proclaimed that Earth had dodged a bullet, and many mentioned that if the space rock had hit our planet, it might have packed a punch comparable to the Tunguska impact in 1908 that flattened trees over an 800-square-mile area in Siberia.
But some fast-tracking observations by MIT Professor of Planetary Sciences Richard Binzel proved that this rock was actually much smaller than that. Likely just 19 meters across, it would probably have disintegrated high in the atmosphere, with only a few small fragments making it to the ground.

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