(meteorobs) Meteoroid streams and the Moon

Roberto G. md6648 at mclink.it
Sun Nov 30 15:40:51 EST 2008


From: "David Entwistle" <David at radiometeor.plus.com>

> Following up on a question from 2006 09 22...
> 
> On 14th December 2008 the almost full Moon will pass within a few 
> degrees of the active Geminid radiant. Does this mean that the Geminid 
> meteoroids that reach Earth, as visible meteors, have passed through the 
> vicinity of the Moon on their way here?  Or, is the alignment of the 
> Moon and radiant just an optical effect and the meteoroids don't get 
> anywhere near the Moon, on their way to Earth?
> 
> I favour the second answer, but am not sure...
> -- 
> David Entwistle

It'a a very complex matter: the meteors fall on the Earth at a speed
of 0-60 Km/sec following the positions of arrival and we ned add
too near 12 Km/sec for the gravitational field of the Earth and that
for meteors coming from all directions, the meteors that come from a
direction very near of the Moon surface are perturbed by the 2 Km/sec
of lunar gravitaional field, but this it's certainly in general not visible
observing meteor showers, but sometime if for exemple the Moon
it's exactly between the observer and the radiant the Moon can to 
focalise meteors as to do Macho with stellar light, but on this matter
I never read papers from professionals. The radiants are in general 
of degree in diameter the the focusing should be only for a very little 
number of meteors. We must too remember that from the Moon at 
the Earth atmosphere there are 384.000 Km that it's, with a meteor 
speed medium around 20 minutes in a near linear travel (as has a 
object not linked at Moon-Earth system), then if  a meteor shower 
it's of little duration as the outburst of November Monocerontids
we perharps to see little changes (minutes) in the time of maximums,
especially for that have little speeds and that are along the ecliptic.
Best greetings.
Roberto Gorelli




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