Originally posted by KILL_DOGG
Tonight is the peak of the Alpha-Centaurids meteor shower. Depending on your location and the cloud cover, you could see 6-8 per hour so not a big
show, but that's what my money is on that you saw.
I wasn't sure if alpha-Centaurids could be seen at the time and location the OP indicated, so I checked the position of the alpha-Centaurid radiant
on the International Meteor Organization web site
using a calendar for a previous year, and marked it
using a red "*". on a screenshot taken of my planetarium software set to simulate the positions of the stars at the time and location the OP saw the
meteor. Here's the shot below.
As you can see, the radiant would have been perhaps 4 or 5 degrees below the horizon at the time (around 21:00 local time or 00:00 UT unless I'm
To explain a little why the position of the radiant is important, the radiant is an area of sky from which meteors of the same shower appear to
radiate from. If it isn't flying away from the radiant, then it can't be a member of that particular shower. Also, if the radiant is too far below the
horizon, then no meteors from that particular shower can be observed at that location.
In this case, the radiant is well within that limit, which is around 10-15 degrees below the horizon. Any alpha-Centaurids observed at this time wold
appear to fly up and away from the horizon since all alpha-Centaurids head away from the alpha-Centaurid radiant, flying south from the NNE.
Alpha-Centaurid meteors observed at this time would be "earthgrazers", which are meteors that graze the edge of the atmosphere (low entry angle) in
comparison to "normal" meteors which plunge down at high angle of entry. Consequently, they tend to last longer and travel over/cover more sky before
they "burn out", which fits the OP's description quite well.
It's not uncommon for earthgrazers to last 5+ seconds, and because the atmosphere is very thin towards the "edge", tails are often not present since
they are made mostly of ionized atmospheric gas.
I posted the following quote just the other day on another thread. Robert Lunsford (Operations Manager and Journal Editor of the American Meteor
Society) writes the following in reply to another observer who saw a meteor with no tail.
Jason and All,
It sounds as if you witnessed a Perseid "Earthgrazer". This occurs when the
radiant lies near the horizon. At this time of night a Perseid meteor enters
the Earth's atmosphere at a shallow angle, allowing it to last much longer
than usual. They often appear as just "dot's" with no visible tail or train.
As the night progresses, Perseids enter the atmosphere at a steeper angle
and then reach the thicker portions of the atmosphere. It is then that they
appear as "normal' meteors with sub-second durations.
I hope this helps!
Source: METEOROBS (The Meteor Observing mailing list)
Lets also not forget that there are other meteor showers and random meteors also occurring at this time (and indeed throughout the year) that could
also account for what imawlinn saw, although there is a good chance it was an earthgrazing alpha-Centaurid. So I think KILL_DOGG is probably right on
edit on 8-2-2012 by C.H.U.D. because: clarification