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Main
Date: 17 Nov 2006 03:09:02
From: Daniel Minge
Subject: Question re meteor showers
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In order to see meteror showers, must it
be the case that the constellation that gives them their name,
eg Leonids has to be above the horizon
On the 19th, the Leonids will be occuring, but Leo won't
rise until the early ours at Adelaide, Australia.
I suppose that if they can be seen whilst Leo is below the horizon,
then the meteors would radiate upwards from the horizon.
Minge
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Date: 17 Nov 2006 03:19:51
From: Chris L Peterson
Subject: Re: Question re meteor showers
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On Fri, 17 Nov 2006 03:09:02 GMT, Daniel Minge <minge@hotmail.com >
wrote:
>In order to see meteror showers, must it
>be the case that the constellation that gives them their name,
>eg Leonids has to be above the horizon
>
>On the 19th, the Leonids will be occuring, but Leo won't
>rise until the early ours at Adelaide, Australia.
>
>I suppose that if they can be seen whilst Leo is below the horizon,
>then the meteors would radiate upwards from the horizon.
When the radiant is at or a little below the horizon, you can still see
Earth skimming meteors overhead. They will point back to the radiant,
but that might not be immediately obvious.
From Adelaide, the radiant of the shower rises at 02:38. You might catch
some a little before this, but basically you only have about three hours
to see anything. The Leonids aren't very well situated for southern
observers (and aren't generally very impressive, anywhere).
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 17 Nov 2006 09:18:45
From: Morris Jones
Subject: Re: Question re meteor showers
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Daniel Minge wrote:
> I suppose that if they can be seen whilst Leo is below the horizon,
> then the meteors would radiate upwards from the horizon.
Keep in mind that meteors are an atmospheric phenomenon, and the Earth's
atmosphere is very thin.
The radiant is a perspective effect, like a train going into a tunnel.
The tunnel walls appear to radiate from the far end of the tunnel as the
train moves through it.
So while you may see some Earth grazing meteors before the radiant
rises, and of course sporadics, the meteors of the shower stream
generally won't be seen -- they'll have missed the thin atmosphere of
the earth.
Some will curve around the Earth a little following a ballistic
trajectory, but for the most part the particles are in a solar orbit and
of such low mass that their path won't change enough to cause them to
hit the atmosphere. The ones that do hit the atmosphere have such a
short life that they don't have a chance to curve around the horizon and
be seen on the far side of the radiant. A good large rock might behave
a bit differently.
Clear as mud? :)
Cheers,
Mojo
--
Morris Jones
Monrovia, CA
http://www.whiteoaks.com
Old Town Astronomers http://www.otastro.org
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