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Re: (meteorobs) New Member Peter Stinson & Request for Info...
Hello, Peter, and a warm welcome to the list!
Your team faces a very difficult problem - the same problem that "fireball
chasers" face when trying to glean useful data from public sightings. In your
case though, lives may depend on making the right call from the data!
I know some of our Olde Meteor Salts will have more to say in response to your
question, but I'll just try to give my $0.02: first, if the event is observed to
deviate in any significant way from a straight (Great Arc) path across the sky,
then it is not a meteor: celestial meteors enter the atmosphere at *minimum*
velocity 11 km/s, and any force which could conceivably shift their visible path
would very likely destroy the object in the process.
(Note the persistent trains or "afterimages" sometimes left behind by meteors
HAVE been known to appear "split" or "kinked", particularly after a few minutes
in the high winds of the upper atmosphere. But I'm talking here just about the
visible light path of the event itself, lasting seconds or less.)
Second, if the event is seen to "hang in the sky" - i.e., travelling with an
angular velocity below a couple of degrees per second, but still lasting more
than a second or two - it is very likely not a meteor or an artificial reentry.
It is POSSIBLE that an extremely foreshortened meteor path - particularly one
which leaves a persistent train - will appear this way. But very rarely.
Finally, there are other things making an event LESS likely to be a meteor,
while not eliminating that possibility altogether: for example, an event which
is seen with a high angular speed in the early evening is unlikely to be a
meteor or an artificial reentry (space junk enters the earth's atmosphere
travelling far slower than meteoroids do!) By the same token, an event with a
very LOW angular speed more than a couple of hours after midnight is less likely
to be a meteor - although again, foreshortening can invalidate this "rule".
Well, you can count on the more experienced readers to correct me where I stray,
Peter. :) But in the mean time, I hope this helps some!
Clear skies and quick rescues!
Lew Gramer
Medford MA
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