Two months ago, NASA observed the largest explosion on the Moon that they've ever seen. And today, they're talking about it and have released a cool video that shows the event as it took place.
The explosion was caused by a meteorite, 0.3 to 0.4 meters wide, weighing in at about 40 kilograms. When it hit the moon, it was travelling at 56,000 miles per hour. According to NASA, it exploded with the force of 5 tons of TNT.
"On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium," says Bill Cooke of NASA's Meteoroid Environment Office. "It exploded in a flash nearly 10 times as bright as anything we've ever seen before."
The impact was so bright, in fact, that anyone looking would have seen it without the help of a telescope.
"It jumped right out at me, it was so bright," says Marshall Space Flight Center analyst Ron Suggs, who was the first to see the impact.
This type of lunar strike is common, but NASA has yet to see one this large in the nearly 8 years its been monitoring the moon for such impacts. Here's why:
Unlike Earth, which has an atmosphere to protect it, the Moon is airless and exposed. "Lunar meteors" crash into the ground with fair frequency. Since the monitoring program began in 2005, NASA’s lunar impact team has detected more than 300 strikes, most orders of magnitude fainter than the March 17th event. Statistically speaking, more than half of all lunar meteors come from known meteoroid streams such as the Perseids and Leonids. The rest are sporadic meteors--random bits of comet and asteroid debris of unknown parentage.
Oh, by the way, the "explosion" is special thanks to the lack of oxygen in the Moon's atmosphere.
"The Moon has no oxygen atmosphere, so how can something explode? 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," says NASA.[NASA via Wired]