A meteorite that smashed into the moon last September caused a bright flash that persisted for 8 seconds, setting a new record for lunar impacts. The high-speed collision was recorded on video and would have been clearly visible to anyone on Earth who happened to look at the moon at the right time, scientists say.
The dramatic lunar impact was spotted by researchers' telescopes near Seville in southern Spain on Sept. 11, 2013. That's when the scientists say a rock the size of a small car — one traveling at nearly 38,000 mph — slammed into the moon. The impact released energy equal to around 15.6 tons of TNT, they say.
The resulting explosion was "almost as bright as the Pole Star, which makes it the brightest impact event that we have recorded from Earth," professor Jose Madiedo of the University of Huelva tells the BBC
"This is the largest, brightest impact we have ever observed on the Moon," says Madiedo, one of four co-authors of a report about the powerful lunar impact published Sunday by the Monthly Notices of the Royal Astronomical Society.
In what may help explain the long-lasting flash, the researchers cite recent theories that suggest visible radiation is "emitted from the condensing ejecta that cool down and form silicate droplets."
Madiedo and his fellow scientists say the impact left a new crater on the moon that likely measures more than 130 feet in diameter. But they caution that specifics about the meteorite's impact are tough to nail down, in part because its origin cannot be determined.
"Two sources have been considered for the impactor," they write. "The event was compatible with the impact geometry of the September Epsilon Perseids minor shower, but it could also be associated with a sporadic meteorid."
The Spanish researchers say the telescopes that spotted the impact are part of a project called MIDAS – for Moon Impacts Detection and Analysis System.
The moon is a ripe research area for meteorite impacts, having no atmosphere to prevent them from hitting home as the Earth does.
It's a certainty that the moon has seen far larger explosions on its surface than the one reported this week. But the blast's power is believed to be triple that of the previous large impact, which was reported by NASA last year.
Madiedo and his colleagues say they'll keep watching for more impacts.
"Our telescopes will continue observing the Moon as our meteor cameras monitor the Earth's atmosphere," Phys.org reports him saying. "In this way we expect to identify clusters of rocks that could give rise to common impact events on both planetary bodies. We also want to find out where the impacting bodies come from."
As Mark reported for the Two-Way earlier this month, A Big Asteroid Just Flew By, And Guess What? More Are Coming.