A lunar Perseid

On August 9th, 2008, George Varros filmed this Perseid-flash in Mare Nubium from his home in Mount Airy, Maryland. "I love watching meteor showers this way," he says. The flash was a little dimmer than 7th magnitude, "an easy target for my 8-inch telescope and low-light digital video camera."

George Varros

"There's more than one way to watch a meteor shower," begins a new Science at NASA story. "One, the old-fashioned way: Find a dark place with starry skies and count the meteors streaking overhead. Two, the new way: Find a dark place with starry skies and then completely ignore the meteors. Instead, watch the Moon. That's where the explosions are."

For centuries, astronomers tried and failed to get solid evidence of the little flare of light that ought to result from a meteoroid hitting the Moon's night side. But that was before modern low-light imaging. About 115 of these events have now been recorded on video, simultaneously from different locations to ensure that they are not point meteors in Earth's atmosphere or glitches in the video chips.

Lunar-meteor watching has become its own little subsection of amateur astronomy. Observers added several more of these events to the archive during the Perseid meteor shower three weeks ago.

I find this too cool for words. A meteoroid just a few inches across will hit with the energy of roughly a hundred pounds of TNT, creating a flash in the lunar vacuum clearly visible to a videocamera on an amateur telescope in a backyard a quarter million miles away. The flashes fade out in less than a second, but they often last for enough video frames to provide good confirmation.

Read more at the NASA story by Tony Philips, which has further links. NASA also has prepared a FAQ and telescope tips for would-be lunar meteor hunters who'd like to get started.


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lee scarborough

September 5, 2008 at 7:51 am

Can these impacts be observed with the eye at the eyepiece, or by camera only?

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Grant Martin

September 5, 2008 at 9:19 pm

I haven't personally observed any lunar impacts at the eyepiece, but if the impact captured on video by George Varros above is typical, they should be easy to see visually with a 6" or 8" scope. Binocular eyepieces would be a big help, though, because the brain is much more likely to register a quick flash if the signal comes from both eyes. The biggest problem with visual observation would be the patience required to watch the dark part of the moon for a long period.
By the way, the best time to detect lunar impacts, either visually or by video, would be around the first-quarter moon. That's when the side of the moon facing us is facing the direction of travel through space. More meteoroids should hit the side of the moon facing us at that time for the same reason you get more bugs on your windshield than on your car's rear window.

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September 5, 2008 at 9:20 pm

This is really neat. Have there ever been any claims of naked-eye visibility of such an event?

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Michael C. Emmert

September 6, 2008 at 12:47 pm

There was another methhod of proxy meteorshower watching after Apollo, that was the seismographs placed on the Moon by the astronauts. That came into play later when an ultraviolet satellite seemed to detect "holes" in the layer of neutral, excited oxygen at the top of our atmosphere. A theory of minicomets was advanced to explain these holes. But is such a scenario, the lunar seismographs would have detected the minicoomets and they didn't. After considerable headscratching they were able to reverse-engineer an electronic error with the satellite that caused a few pixels to blank out.

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Greg McCauley

September 8, 2008 at 7:46 pm

I would like to find a listing of other worthwhile projects amateur astronomers can get involved with. Anyone know of any resources?

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