Sometimes one gets away. That’s how it looked back in 2010 when the Catalina Sky Survey spotted the faint asteroid 2010 WC9 on November 30. Astronomers tracked it until December 10, when it became too faint to see. Unfortunately, that wasn’t enough time to nail down an orbit and predict its next return, so the asteroid was considered lost. Then on May 8, 2018, some 7½ years later, astronomers discovered an asteroid they temporarily named ZJ99C60. After determining a preliminary orbit, they realized it was a match for 2010 WC9. Lost was now found.
2010 WC9 makes a very close pass of Earth today (5:05 p.m. Central Time) at just half the distance of the moon zipping along at 28,655 miles per hour (46,116 km/hr). This is a substantial space rock, measuring about 295 feet (~90 meters) across, but of no danger to the planet. It will pass right on by. Earlier this morning, amateur astronomers with larger telescopes saw it as a faint 13th magnitude “star” in the constellation Ophiuchus. When closest, it will be hurtling across the southern constellation Pavo the Peacock at magnitude 11, visible from the Caribbean and points south and shining at magnitude 11, bright enough to spot in a 6-inch telescope. In and out — that’s how it is with these close-approaching asteroids.
They’re extremely common with many new discoveries made every month. 2010 WC9 is an Apollo asteroid, named for the first of its class discovered, asteroid 1862 Apollo. There are about 1,600 known. Apollos cross Earth’s orbit and so have the potential to collide with our planet sometime in the future. Is 2010 WC9 one of these bad boys? Rest easy — nothing’s in the cards for 100 years or more.