In 2036, an asteroid bigger than two football fields will pass within 23,000 miles of the Earth. For some reason, Russian astronomers seem convinced that this asteroid will strike the planet and cause a major disaster. But American scientists say that's almost certainly not going to happen.
The asteroid is called 99942 Apophis, and it's been in the news before. In 2004, when Apophis was discovered, people were briefly worried that it would smash into the Earth 25 years hence. NASA had even calculated the date: April 13, 2029. But eventually scientists walked it back, saying that no, we weren't in any danger from Apophis. Now, Leonid Sokolov, a professor at Saint Petersburg State University, has said it's "likely" that Apophis will hit the planet, for real this time, in 2036--once again, on April 13.
Donald Yeomans, manager of NASA's Near-Earth Object Program Office, has responded to Sokolov, explaining that "likely" actually means not very likely at all. In order for Apophis to hit the Earth in 2036, it first needs to get snagged in what's called a "gravitational keyhole"--per United Press International, this is a region of space about 2,000 feet across, where gravity would alter the asteroid's course and point it toward our planet. According to Yeomans, there's a one-in-250,000 chance of this happening. And even if Apophis does pass through the keyhole, he says, we'd probably be able to figure out some way to divert it.
Readers with long memories may recall similar stories about 1997 XF11, 2003 QQ47, and 2002 NT7, all doomsday asteroids that turned out not to be such a big deal. Right now, it looks like Apophis belongs in the same category. And it seems worth asking at this point whether there's some other, unreported significance to the date April 13, like maybe it's the birthday of an unpopular astronomer somewhere. "Nope, sorry Dave, we can't have a party for you. Yeah, no, the sky is gonna be choked with dust and water vapor, so..."