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Re: (meteorobs) Radiant Diameter vs Radiant Activity Period
Again, George, the determining factor for radiant size is the distribution
of DIFFERENT orbits among the particles that make up the stream. If you can
imagine a hypothetical stream where all the meteoroids were moving in
EXACTLY parallel paths through space, the radiant diameter would (I assume)
be zero degrees... (Though it's possible differences in the effect of
earth's gravity acting on meteoroids with different trajectories would still
result in some small spread? So maybe there is actually a minimum radiant
size, actually dependent on the speed and relative orientation of the shower
stream with respect to earth's orbit?)
Anyway, this theoretical "perfect stream" could be light years wide, and the
persepctive effects of radiants would still make all the meteors appear to
radiate from a single very small area in the sky. Of course, thinking about
it, such a perfect stream may not be able to exist, except for showers which
lasted no more than a single night... After all, for the earth to encounter
the stream across many successive nights, it must be encountering particles
with successively greater (or lesser) perihelion distances. Not sure how the
orbital geometries could work out for a theoretical case like that!
Clear skies all,
Lew
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