Don't worry, we're not going to have to call Bruce Willis and Ben Affleck in to fly out and save the planet. But tonight a pretty large asteroid is going to fly closer to the Earth than any asteroid has in two centuries, and if you've got a telescope and a little knowledge, you'll be able to see it.
The asteroid in question is 2005 YU55, a 400-yard-wide space rock that will pass by the Earth this evening (evening for Americans, anyway) at a distance of only about 201,700 miles, 10 percent closer to us than the moon.
Scientists have known about the asteroid's path since 2010, and while they always knew there was no danger of it hitting us, they are seeing this as a unique opportunity to study an asteroid up close, taking note of its dimensions, shape and even topography for future reference in asteroid study.
Something the width of four football fields is pretty huge, but from more than 200,000 miles away it's pretty hard to see. If you have a little equipment, though, NASA says you should be able to spot it.
"400 meters, I'd say, is a moderate size asteroid, but it's still small and very far away. You'll need at least a six-inch telescope in order to be able to observe it. You'll see it buzzing really fast along the sky," said NASA astronomer Marina Brozovic.
The object will gain nighttime visibility at 6:28 p.m. EST tonight, and viewers watching the sky in North America and Western Europe have the best chance to see it.
"The pass' track is especially favorable for western Europe and North America. But you'll need to know exactly where and when to look," said Kelly Beatty, senior contributing editor at Sky & Telescope magazine. "The object will traverse the 70 degrees of sky eastward from Aquila to central Pegasus in just 10 hours, clipping along at seven arcseconds per second."
If you're not sure exactly what Beatty is talking about there, here's a sky chart to help you along.
The path of 2005 YU55 is a pretty close call, sure, but the asteroid is too small to affect any gravitational patterns on Earth. And don't worry; NASA has already thought ahead, and there doesn't seem to be any danger of the asteroid hitting us on a future visit either. At least, not for a while ...
"We have a very good idea about its orbit for the following hundred years, and there is no chance of impact," said Brozovic. "We believe with these upcoming measurements at Arecibo and Goldstone we will remove this threat even further—probably for many centuries."