moon impacts

[jackdavinci]

The Earth’s atmosphere prevents a lot of outer space objects from impacting, but the moon has no guard against these projectiles. What’s the largest moon impact that has been 1) witnessed 2) documented 3) filmed?

[Sam_Stone]

The largest crater on the moon was only recently discovered: The Aitken Basin The cite says it’s actually the largest known impact crater in the solar system - 1300 miles wide.

[RickJay]

I’ve heard of some people claiming to see flashes of light but I do not believe there has ever been a verified observation of the Moon being struck by an object of substantial size.

It’s true that the Moom lacks an atmosphere to stop meteors, but really big strikes are still very rare. Scientists have also theorized that the far side of the Moon, which we don’t see too often, takes the majority of hits.

[Fear_Itself]

@RickJay

I’ve heard of some people claiming to see flashes of light but I do not believe there has ever been a verified observation of the Moon being struck by an object of substantial size.

Thanks to rowrrbazzle, we now know that a lunar meteor strike has been filmed:

There’s a new crater on the Moon. It’s about 14 meters wide, 3 meters deep and precisely one month, eleven days old.

NASA astronomers watched it form: “On May 2, 2006, a meteoroid hit the Moon’s Sea of Clouds (Mare Nubium) with 17 billion joules of kinetic energy—that’s about the same as 4 tons of TNT,” says Bill Cooke, the head of NASA’s Meteoroid Environment Office in Huntsville, AL. “The impact created a bright fireball which we video-recorded using a 10-inch telescope.”

[chorpler]

Wasn’t there some enormous impact in the 11th century that was witnessed by some monks in Asia? I have a vague recollection of reading something like this somewhere.

[Q.E.D]

@chorpler

Wasn’t there some enormous impact in the 11th century that was witnessed by some monks in Asia?

Close. It was one monk, by the name of Gervase of Canterbury, who witnessed a flash of light on the Moon, later thought to have been an asteroid impact. Some astronomers believed that a crater called Giordano Bruno was the result, but some doubt has been cast on this in recent years. See here.

[KGS]

I know it’s not the moon, and the impact itself wasn’t actually photographed, but Comet Shoemaker-Levy deserves honorable mention for being the largest planetary impact ever witnessed.

[diggleblop]

I thought the moon was made of cheese? :^/

[chorpler]

@Q.E.D.

Close. It was one monk, by the name of Gervase of Canterbury, who witnessed a flash of light on the Moon, later thought to have been an asteroid impact. Some astronomers believed that a crater called Giordano Bruno was the result, but some doubt has been cast on this in recent years. See here.

Was he one of the group of five people that the article says saw the impact?

Thanks for that link. Fascinating stuff. That sure is a big crater, or at least it threw out a lot of stuff. How come that was linked with the incident in 1178 in the first place? How do we know that’s about when that crater appeared?

[Peter_Morris]

I heard that that moon is still shaking as a result of the impact, and the shakes can be detected by sensitive equiptment. Is this right?

[Squink]

@Peter Morris

I heard that that moon is still shaking as a result of the impact, and the shakes can be detected by sensitive equipment. Is this right?

The shaking probably doesn’t last for days, however:

Furthermore, shallow moonquakes lasted a remarkably long time. Once they got going, all continued more than 10 minutes. “The moon was ringing like a bell,” Neal says.

On Earth, vibrations from quakes usually die away in only half a minute. The reason has to do with chemical weathering, Neal explains: “Water weakens stone, expanding the structure of different minerals. When energy propagates across such a compressible structure, it acts like a foam sponge—it deadens the vibrations.” Even the biggest earthquakes stop shaking in less than 2 minutes.

The moon, however, is dry, cool and mostly rigid, like a chunk of stone or iron. So moonquakes set it vibrating like a tuning fork. Even if a moonquake isn’t intense, “it just keeps going and going,” Neal says.