The asteroid Apophis sits atop a shortlist of potentially dangerous objects that could one day hit Earth. And in March, the aircraft carrier-sized asteroid will make its final close path to Earth before 2029, a year when astronomers once wondered if it would strike our planet. We now know Apophis won't hit Earth anytime soon, but the upcoming flyby will still provide a relatively rare opportunity to study the space rock up close.
As the asteroid draws near, it will also make a fortuitous pass in front of a relatively bright star, letting amateur astronomers get in on the action. On Sunday, February 21, at around 11:50 P.M. Central Time, Apophis will move across the face of a distant star, creating what astronomers call an occultation. It’s like a miniature version of what happens when Earth’s Moon eclipses the Sun. Such occultations are a great chance to learn more about the size, shape and composition of planetary bodies.
In the past century, occultations have yielded a range of insights into distant objects that would’ve been otherwise hard to discover from Earth. Pluto’s faint atmosphere and the rings of Uranus, for example, were both discovered when those planets occulted distant stars.
