7:43am

Sat May 18, 2013
The Two-Way

WATCH: NASA Spots Brightest Lunar Explosion Ever Recorded

NASA scientists say they witnessed an extremely bright lunar explosion this past March. In fact, it is the biggest explosion they've seen since they started keeping track of such events in 2005.

"On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium," Bill Cooke, of NASA's Meteoroid Environment Office, said in a press release. "It exploded in a flash nearly 10 times as bright as anything we've ever seen before."

What's cool is if you had been looking at the moon at just the right time, you would have seen a one-second flash caused by the impact of a nearly-90 pound meteoroid that was traveling at 56,000 mph. The impact was picked up by one of the Meteoroid Environment Office's 14-inch telescopes.

One intriguing question is how a meteoroid can cause an explosion on the Moon, which has no oxygen atmosphere.

NASA explains:

"Lunar meteors don't require oxygen or combustion to make themselves visible. They hit the ground with so much kinetic energy that even a pebble can make a crater several feet wide. The flash of light comes not from combustion but rather from the thermal glow of molten rock and hot vapors at the impact site."

Since NASA started keeping tabs of lunar strikes, it has counted more than 300 of them. They hope keeping track of these events will help them make decisions during long-term lunar missions.

"Is it safe to go on a moonwalk, or not?," NASA asks. "The middle of March might be a good time to stay inside."

We'll leave you with a graphic that shows all of the strikes the NASA program has recorded. The red square marks the spot of the March 17 impact:

Copyright 2014 NPR. To see more, visit http://www.npr.org/.