Asteroid 2010 WC9 will safely pass at about half’s the moon’s distance on Tuesday, May 15, 2018. Estimates of its size range from 197 to 427 feet (60-130 meters), making the May 15 pass one of the closest approaches ever observed of an asteroid of this size. This asteroid was “lost” and then found again. The Catalina Sky Survey in Arizona first detected it on November 30, 2010, and astronomers watched it until December 1, when it became too faint to see. They didn’t have enough observations to track its orbit fully and so predict its return. On May 8,...
