On November 7 of this year, a small meteoroid hit the Moon.
Two astronomers have set up a small telescope with a CCD video camera to see if they could capture the faint flash from a lunar impact. And they nailed one on their first night! It’s almost certainly an impact; they investigated other possible causes (a satellite flash, a meteor in the Earth’s atmosphere, a cosmic ray zapping their equipment) and were able to rule them out. It looks real to me.
There have been other meteoroid impacts seen in the past. In fact, there has been a rich history of flashes on the Moon, collectively called "Lunar Transient Phenomena". Some areas seem prone to them; the crater Aristarchus once had a red flash in it which some people thought might have been volcanic! But it was never confirmed.
Years ago, that got me thinking. I got interested in setting up a project to observe these flashes. If they are meteoroids, then you need to look at the dark part of the Moon. Your best bet would be a small ‘scope that could see the entire Moon at once, and a video camera that takes thousands of individual frames. It would have to automatically process them; take an image, take a second image, subtract them, and look for a place where the brightness has suddenly changed. You’d need a robotic telescope, but it wouldn’t even have to be a dark site, since the flashes are fairly bright…
In the end, it was a pretty big undertaking for one guy. I told a few folks about it and they agreed it would be interesting, but a pain to set up. Also, getting a grant to do it would be a big time sink, and I was busy at the time (I was just starting to write my book). So I never pursued it.
Actually, this would be a relatively easy thing for an amateur to do now. A six-inch telescope would probably be enough, in fact. The flash seen in November was at 7th magnitude, which is not hard to spot with binoculars, so even a small ‘scope would do it. And, in fact, having more people doing this is important, vital even– it can help distinguish real lunar impacts from something local (like a satellite or airplane). If two different telescopes at widely different locations spot it, that makes the case pretty solid for an impact.
Tip of the BABlog hat to Larry Kellogg’s Lunar Update Mailing List for this tidbit.