Asteroid Apophis to pass near Earth on Wednesday

Nostalgic for last year's Doomsday worries? You may enjoy pondering an asteroid, named Apophis, passing overhead Wednesday. It also aims for close encounters with Earth in 2029 and 2036.

The asteroid, some 880 feet or more across, will pass within 9 million miles of Earth on Wednesday, its closest approach this year. The asteroid had attracted a great deal of interest in 2004, when it was discovered, after some estimates suggested it had a chance of hitting Earth in 2036. That possibility was later dismissed after better estimates of its orbit arrived.

Because a tiny chance still exists of the asteroid hitting Earth in 2036, "scientific interest in Apophis is acute, and it's very important to learn as much as we can about this object when it gets close enough for physical observations," says a recent statement from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Radar observations of the asteroid, scheduled for February, should refine orbital track analyses of the asteroid's impact chances.

If it ever hit Earth, the asteroid would deliver an impact blast on land of 141 megatons, almost three times stronger than the biggest H-bomb ever tested, according to Purdue University's impact calculator.

"Due to the proximity of its orbit to Earth, Apophis is being considered as a potential target for both robotic and crewed spacecraft missions," the JPL statement notes.

But instead of any landing this year, the Wednesday night passage will be too dim for even backyard telescopes, says Slooh Space Camera's Patrick Paolucci, in a statement. Slooh's online cameras will make views of the asteroid available in a webcast on Wednesday night.

Overnight, Europe's Herschel space telescope has taken new views of the asteroid, finding it larger than expected, possibly measuring about 1,070 feet across.

"Right now is as close (as bright and observable) as Apophis gets between now and 2029," says MIT asteroid expert Richard Binzel, by email. "For anything we might plan to do in 2029, (say) send a spacecraft to observe it, now is the time to get the best data on Apophis to plan that mission."