Mystery Moon Flashes Caused by Meteorite Impacts

by Paul Scott Anderson on January 27, 2012

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Example of a lunar flash, photographed in 1953. Credit: Leon Stuart/Columbia University Department of Astronomy

For hundreds of years, people have seen tiny flashes of light on the surface of the Moon. Very brief, but bright enough to be seen from Earth, these odd flashes still hadn’t been adequately explained up until now. Also known as Transient Lunar Phenomena (TLPs), they’ve been observed on many occasions, but rarely photographed. On Earth, meteorites burning up in the atmosphere can produce similar flashes, but the Moon has no atmosphere for anything to burn up in, so what could be causing them? As it turns out, according to a new study, the answer is still meteorites, but for a slightly different reason.

The lights don’t result from burning up as on Earth, but rather are hot blobs of material produced by the impact itself. The impacts were calculated to be powerful enough to melt the meteorites, producing super hot liquid droplets, called melt droplets, that produced light as they formed and then began to cool afterwards. The meteorites themselves can be tiny, but still cause an impact that could be seen from Earth.

Sylvain Bouley, a planetary scientist at the Paris Observatory and co-author of the study, explains: “You have just a small piece of cometary material or asteroid, about 10 centimeters, that can do a very bright flash visible from the Earth.”

Fellow planetary scientist Carolyn Ernst of Johns Hopkins University’s Applied Physics Laboratory, adds: “Something is melting, and because it’s so hot, it radiates in the visible wavelength until it cools down.”

The study included observations from 1999 – 2007, for which the brightness of the flashes and sizes and speeds of the meteorites were calculated.

The impacts have also been replicated at the Meteoroid Environment Office at the Marshall Space Flight Center, where tiny aluminum spheres were shot into simulated lunar dirt. The results were similar, helping to confirm the other team’s findings.

Other previous possible explanations included reflections on the Moon by tumbling satellites or even volcanic activity. There may still be debate though, as an earlier report in 2007 had attributed the flashes to outgassing on the Moon’s surface.

The paper will be published in the March 2012 issue of Icarus.

About 

Paul Scott Anderson is a freelance space writer with a life-long passion for space exploration and astronomy and has been a long-time member of The Planetary Society. He currently writes for Universe Today and Examiner.com. His own blog The Meridiani Journal is a chronicle of planetary exploration.

Stan Taylor January 27, 2012 at 6:39 PM

Sounds like a job for the Mythbusters.

Torbjörn Larsson January 27, 2012 at 7:01 PM

Hot diggity dirt!

Anonymous January 27, 2012 at 7:43 PM

Given the number of meteors that hit Earth every day, it’s logical to assume that these flashes are impact events.

Tammy Plotner January 28, 2012 at 12:46 AM

great article, paul! wouldn’t you love to catch one of these while observing? of course, unless you were videoing the moon at the time, you might not want to believe your own eyes. ah, my… no wonder some of us get into LTP work! thanks for reminding readers that there are many reasons to observe the moon!

Paul Scott Anderson January 28, 2012 at 12:58 AM

Thanks, Tammy. Yeah I would, I’ve never seen one yet. I need to get a new telescope though too… :-)

Anonymous January 28, 2012 at 9:32 AM

Wikipaedia has a good article…

http://en.wikipedia.org/wiki/Transient_lunar_phenomenon

I particularly like the Canterbury Monk’s description.

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