A giant asteroid will pass in front of a star, blacking it out for a short period of time. Viewers in the northeastern United States will be able to watch it happen live, weather permitting.
163 Erigone, an asteroid the size of Rhode Island, will pass in front of Regulus on Thursday night, just after 2 a.m. EST. This occultation of the star by Erigone could last 14 seconds. The asteroid measures 45 miles from one side to another.
Occultations of stars by asteroids and other bodies are fairly common, but usually affect much dimmer stars. This is just the eighth time in the last 35 years such an event will be visible with the naked eye.
Anyone in the New England or New York will be able to see this astronomical occurrence without any special equipment. Simply go outside (remember to dress warm!) and look for Regulus. The star will be found high in the western sky. Look for the constellation, resembling a body and head, with its head angled down, to the right. Regulus will be the bright star at the bottom right of the lion's body. The constellation resembles a question mark to many people. The occultation will take place at 2:06 a.m. For people in the northern reaches of the area where this can be seen, the occultation will happen a few minutes later than it will further south.
163 Erigone is extremely dark, nearly the color of asphalt. The asteroid was discovered in 26 April 1876, by the French astronomer Henri Joseph Perrotin. The astronomical body was named after one of the two Erigones in Greek mythology. The carbon-rich asteroid rotates once every 16 hours.
Observers can contribute data on the observation for use by astronomers. All you need is a stopwatch, SLR camera or video camera. Astronomers are looking for the exact amount of time for which Regulus is blacked out, and your precise location. Putting these data points together can help researchers determine the exact size and shape of the giant asteroid. Amateur astronomers can submit their raw data to the International Occultation Timing Association.
Regulus is the brightest star that will be occulted by an asteroid visible from North America for decades. So, this event could be a once-in a-lifetime occurrence.
The group collecting the data has even produced a smartphone app, available on their Web site, to time the event.
Let's hope the weather cooperates, giving viewers a chance to witness this rare event.