It’s pretty clear by now that a space rock ranging somewhere in size between an acorn and a football hit the darkened moon during Sunday night’s total lunar eclipse. But were there two?
Confirmations of the first impact, and reports about the second, have been circulating through the scientific community and the Twitterverse over the past couple of days.
The first report, posted to a Reddit discussion forum, noted a brief flash of bright pixels on pictures of the moon taken at around 4:41:43 GMT Jan. 21 (8:41:43 p.m. PT Sunday), just as the eclipse was going into its total phase. The location of the flash was in an equatorial region west of Mare Humorum near Lagrange Crater
Skywatchers quickly compared notes on Twitter, with Stony Brook University geologist (and amateur astronomer) Justin Cowart among the leading sleuths. The flash showed up on cameras in California, Pennsylvania, Morocco and the Netherlands, boosting the view that it wasn’t just a camera glitch.
Definitive word came from the University of Huelva’s Moon Impacts Detection and Analysis System, or MIDAS:
The impact flash has been recorded by telescopes operating in the framework of MIDAS Survey from Europe https://t.co/dJzPWmBCUp
— Jose Maria Madiedo (@jmmadiedo) January 22, 2019
Lunar impacts have been observed before, by MIDAS as well as by NASA’s Meteoroid Environment Office. The NASA program spotted 33 in 2017 alone, most of them associated with the Geminid meteor shower in December of that year. It’s unusual to spot one during a total lunar eclipse. But how unusual?
On one hand, lunar eclipses last no more than a couple of hours, cutting down on the duration of the viewing opportunity. On the other hand, it’s possible for oodles of eyes to be turned toward the moon during that brief time — as evidenced by the plethora of tweets hashtagged #eclipseimpact.
Astronomers at Britain’s Royal Observatory wound back the video and reported a second meteor flash, taking place just a little more than two minutes after the first flash at a point on the other side of the moon’s darkened disk:
Looking back at our footage of the #TotalLunarEclipse on 21 January, our astronomers spotted two bright flashes on the Moon – meteoroid impacts – separated by just over two minutes (and thousands of miles!) Hey, @LRO_NASA, time to look for new craters! pic.twitter.com/G7hwUAWpPq
— Royal Observatory (@ROGAstronomers) January 23, 2019
As hinted in the tweet, before-and-after images from NASA’s Lunar Reconnaissance Orbiter could document how the impact, or impacts, changed the moon’s terrain. That could give scientists a better sense of how often the moon gets hit, and how hard. Such information could be key for planning future human settlements.
“This is a great opportunity for shared science,” LRO project scientist Noah Petro said in a tweet addressed to his fellow astronomers. “I’m asking to archive your data, let’s try to coordinate data (duration of flash for one).”
LRO’s scientists have already documented the aftermath of a significant lunar impact observed in 2013. But to follow up on this week’s eclipse observations, astronomers will have to focus in on exactly where the space rocks hit, and then figure out whether the orbiter has post-impact imagery of the same area. That can’t happen in the blink of an eye, particularly with a government shutdown going on.
“The WolfSuperBloodMoon Crater will take time,” Petro tweeted.
Hat tip to Kimberly Cartier and the American Geophysical Union. Check out Cartier’s report on Eos.
