On November 8th, the asteroid YU55 passed within about 200,000 miles of the Earth. To capture this rare (and a little frightening as the asteroid had a diameter of around a ¼ mile) event, the observatory telescope took a series of 8 ten-second exposures which were then stitched together into a movie. The animation shows just how fast the asteroid is moving with respect to the earth (about 13km/s or 29,000 miles per hour, according to NASA). In fact, it is moving so fast that in each image it looks like a streak, rather than a dot, over the 10 second exposure.