2002 AM31 swings by Earth tomorrow evening at 13.7 lunar distances. The diagram shows its position near Earth this morning (July 21). Credit: JPL/NASA

An Earth-approaching asteroid discovered in 2002 will be passing through the neighborhood Sunday night (July 22). 2002 AM31, a leftover fragment of rock from the solar system’s youth, will fly safely by Earth at a distance of 3.2 million miles (13.7 times the distance to the moon) around 8 p.m. (CDT) July 22.

With a diameter estimated between 1,115 and 2,600 feet, 2002 AM31 is bigger than many close approaching asteroids. Pity it won’t be very bright – only 14th magnitude – but savvy amateur astronomers with 10-inch or larger telescopes can track it in the northern sky as it creeps through the constellation Cepheus. To get a list of it hour-by-hour positions that you can plot on a star atlas, click HERE and then click the “Generate Ephemeris” button.

If you don’t have the equipment, no worries. The SLOOH Space Camera will broadcast the asteroid flyby live beginning 6:30 p.m. (CDT) Sunday. Because of its relatively small size and distance, 2002 AM31 will look like a “star” moving across a field of background stars. I’ve watched these webcasts before and they’re a lot of fun. You not only feel like you’re “right there” in real time, but you’ll learn a lot about asteroids from the accompanying commentary.