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triceretops
06-13-2012, 03:55 AM
Hi, I just had an editor tell me that meteorites hitting the moon, even if you were on the moon's surface, would not leave any type of atmospheric contrail or friction flash. I know that the moon has a very thin atmosphere (nearly non-existent) but it does have one.

My question is whether incoming meteorites would show themselves by any type of a contrail streak, barely visible or not. If not, would they flash, even slightly, upon impact?

I would think they would send up a substantial impact plume of lunar dust, eh?

I researched all over the place but couldn't find an answer to this. It has me gobsmacked.

tri

blacbird
06-13-2012, 06:16 AM
Hi, I just had an editor tell me that meteorites hitting the moon, even if you were on the moon's surface, would not leave any type of atmospheric contrail or friction flash. I know that the moon has a very thin atmosphere (nearly non-existent) but it does have one.

My question is whether incoming meteorites would show themselves by any type of a contrail streak, barely visible or not. If not, would they flash, even slightly, upon impact?

No. The atmosphere of the moon is so diaphanous and close to the surface that no significant interaction with an incoming object would be noticeable.


I would think they would send up a substantial impact plume of lunar dust,

Whatever physical material got ejected from the impact would fall back to the surface under the standard acceleration of lunar gravity. The Apollo astronauts demonstrated this in their travels across the surface, which kicked up lunar dust that fell very quickly, leaving no "plume". To get a dust plume, you need a much more substantial gaseous envelope that can support small particles.

In a significant impact, there would be heat and a flash of light, lasting however long it took for the impacted material to cool below the glowing point. But, unlike the 1994 cometary impact on the atmosphere of Jupiter, no "plume" would be generated.

One such event might actually have been seen by human eyes. Some hundreds of years ago a group of monks recorded "a fire on the moon", which may have been observation of a bolide impact.



eh?

Don't go getting all Canade on me, eh?

caw

triceretops
06-13-2012, 06:47 AM
Thanks, Robert. You sound spot on, here (now I'm going Brit on you).

So the most I could hope for would be a flicker of light (nearly instantaneous) at the impact point, provided it was a significant object. This is a shower. The witnesses have a very good vantage point.

How embarrassing for a SF writer and amateur astronomer to get called on this. Gak.