Aristarchus Plateau (and crater) on the Moon, courtesy Hubble Space Telescope.
A couple of days ago, just after I wrote here about humanity’s return to the Moon, I got an email from the web editor at Scientific American, pointing out an article about an interesting idea from a scientist who hopes to explain the phenomenon of lunar transients. The article, called Lunar “UFOs” May Be Volcanic Belches, describes work done by Arlin Crotts of Columbia University. He has been studying what he calls a “hairball of a data set” containing reports of flashes on the Moon’s surface that date back many years. In fact, people have been reporting strange flashes on the lunar plains since the 1500s. Crotts’s idea is that the flashes, if they really do exist, are the result of dust stirred up by emissions of radon gas belched out from under the lunar surface. Many of these “transients” appear to happen around the crater Aristarchus, which is known to be the most volcanically active region of the Moon in the past.
Crott’s idea is that volcanic gas is escaping from the lunar interior. When it reaches the surface, it disturbs the dust, creating what looks like a flash of light (since the dust is reflecting sunlight).
Now, it sounds plausible, but I was a little skeptical—as are other planetary scientists who are nonetheless interested in the idea. There are many questions about the interpretation he’s making, most of which can be answered with more research and data.
The first objection that popped into my head as I read the article (and I was glad to see somebody else bring up) is that these things, by their very nature, are transient. That makes them hard to predict and observe, and prediction and observations are at the heart of understanding what’s happening here. To really determine the cause, we need to observe more of them under more rigorous conditions. Crotts anticipates this and is setting up a robotic imaging system to track the Moon and watch for transients.
I suppose when we return to the Moon, lunar geologists will be able to study these phenomena in real time, which is a good argument for having people there to do the work. Not only will they be able to measure the emissions, but they can also monitor seismic conditions more closely and do more extensive surveys of the geologic makeup of the regions where these “UFOs” are lighting up the surface.
(Not that these are UFOs. I’m just echoing the headline, which uses the term “UFO” in quotes to indicate that they know these things aren’t little green men or aliens from the Pleiades or other nonsensical beings that the tinfoil crowd brings up every time there’s an unusual sighting in the sky.)