Originally posted by Nerdling
Should I call my local observatory?
No. You should go outside and enjoy the show!
However, if it had taken place on a non-major shower night, and the meteor was exeptionally bright (or accompanied by any unusual phenomena like sonic
booms/major fragmentarion/your face peeling off your skull), then that would have been pretty much the right thing to do
Seriously though, you should contact the
International Meteor Organization (IMO) or the
American Meteor Society has an
online fireball
report form if you see something like I described above.
Bright meteors are fairly common, but super-bright meteors (ranging from the brightness of a full moon to the brightness of the sun), are increasingly
rare in proportion to their brightness, and whitness reports of such events are eagrly sought in the scientific community, so I'd encorage anyone
reading this to report their sighting to one of the organizations mentioned above.
Originally posted by _Phoenix_
Hey I wonder if you or anyone else can answer this.
I saw the first shooting star go by, then 3 mins later I saw another but this time it went in the total opposite direction!?
Is that normal?
The Anonymous answer above is right on the mark, but since this is ATS, I think this topic deserves a more in-depth answer...
Just to help illustrate the point, heres a photo showing the Leonid radiant, and many meteors appearing to radiate away from it. Notice how the
meteors closest to to the radiant appear to be short, and those further away look longer? Well, not all of them, but in general...
source
...well that is just an optical illusion!
When you see a meteor very close to it's radiant, it looks short because you are looking at it heading directly (or close to directly) towards
you.
Conversely, meteors seen to appear far away from the radiant (typically seen early on in the night when the radiant is just about to rise or has
already risen but is still withing a few degrees of the horizon), can be long and breathtakingly spectacular, and are known as "earth-grazers". Due
to them hitting the atmosphere at a very shallow angle, they tend to survive longer, and that combined with the side on (vs "head on") perspective
makes for extremely memorable meteors!
Meteors seen actually
in the radiant (rather than a point, the radiant is actually a small area of sky, but it's easier to talk in terms of it
being a point for simplicities sake usually) will appear as stationary points that grow in brightness and quickly fade away.
So, if you are looking towards the radiant, as Phoenix seems to have been back in August, and a meteor appears somewhere to the left of the radiant,
travelling away from it, followed by a meteor just to the right of the radiant travelling in the exact opposite direction to the first meteor, the
second has to also be travelling away from the radiant.
The important thing to remember here is that
all meteors travel away from the radiant (of the shower they belong to).
Now, to confuse things yet further, all meteoroids (a meteor is the name for the light show you see when a meteoroid slams in to the atmosphere)
belonging to a particular meteor shower are travelling on parallel trajectories in respect to each other - just like a formation of aircraft flying
straight and level, except that this particular formation is usually following a comet in a never ending chase around the sun, just like a dog chasing
it's tail.
I've uploaded a short .mov (leonids.mov) which is an animated simulation of how the Leonid dust-trails interact with Earth (same principal for the
Perseids and all other well defined showers), to give the illusion of an imaginary point in the sky called a radiant from which all meteors belonging
to that shower appear to radiate from.
Also in the zip is a CGI animation/simulation of the formation of a Leonid dust-trail (here's where the dog chasing it's tail comes in). In this
case the meteoroids being simulated were ejected from the parent comet in 1767. The inner red ring represents Earth's orbit around the sun, and the
outer red ring represents Jupiter's Orbit around our sun.
Jupiter has to be included in any orbit simulations where orbits come close, since gravity is so massively strong due to Jupiter's sheer size, it's
effects on comets and the meteoroids forming a dust-trail can also be so great that the trails become perturbed whenever they come close, directly
affecting future shower predictions for that stream.
The Zip can be downloaded from here:
www.sendspace.com...
I hope that helps, if not, just ask
[edit on 13-9-2008 by C.H.U.D.]