(meteorobs) Meteoroid streams and the Moon

[David Entwistle]

In message 
<c7cc1f220811301255r1514e1dex3a23b28a0666110c at mail.gmail.com>, Shy 
Halatzi <shyhalatzi at gmail.com> writes
>From what I thought so far (I'm not an expert so I may be mistaken), 
>the
>direction of the radiant is not really the direction from which the
>meteoroids arrive from in space.

Chris, Wayne, Roberto and Shy,

Thanks for you comments.

My rough and ready calculation (which is very probably incorrect) for 
the Geminids, in the plane of the ecliptic, has:

Earth's approximate velocity:
(149.6 x 10e6 x 2 x Pi)/(356.25 x 24 x 60 x 60) = 30 km/s
Moving towards the Apex of Earth's way at 172 degrees ecliptic longitude 
(Ophiucus).

Geminid meteoroid's approximate apparent geocentric velocity (the 
resultant):
35 km/s (that's Vinf, if that's right to use)
112 degrees ecliptic longitude

Roughly plotting the vectors on paper, I think that if we could somehow 
stop and 'park' the Earth in its orbit, then the Geminids would appear 
to radiate at 34 km/s from Taurus at 61 degrees ecliptic longitude, near 
the Hyades. This is the area where the Moon will be on 2008 12 11 15:00.

Those meteoroids passing by the Moon will take 384,400 / (35 x 60 x 60) 
= 3 hours to reach Earth. So, any effect would be seen in the early 
evening of 11th December. If it's clear, I'll certainly have a look.

Best wishes,
-- 
David Entwistle