(meteorobs) Imagining ourselves following a vehicle along a dusty road...

[Geert Barentsen]

Hi Alex,

Just to illustrate what Nikola said, have a look at an illustration: 
http://www.spmn.uji.es/ESP/radiant.gif

The big yellow arrows illustrate how the parallel meteors are being 
projected differently onto the observer's sky (perspective effect...)

Geert



At 11:50 20-2-2006, you wrote:
>At 11:28 20.02.06, you wrote:
>>Hello all, I am a new member of the mailing list, and I have a question
>>which has built up in my mind and which I wondered if I might empty into
>>your gracious inboxes, with permission.
>>
>>Its about radiants. Now as I understand it, meteor showers are the
>>product of the intersection of our spherical earth with a somewhat
>>cylindrical region of comet/asteroid debris. This being the case, how is
>>it that meteors appear to radiate from a single point in the sky? I
>>would have imagined that they would appear from along a path in the sky
>>that is traced out by the length of the debris trail. The only time I
>>would expect meteors to come from a single point at any one time would
>>be if the path of the comet/asteroid was very similar to that taken by
>>the earths orbit, then it would appear like we were following a jet's
>>vapour trail through the sky, or a vehicle along a dusty track, which in
>>each case would produce a 'radiant' or source of material which was a
>>single point.
>
>It's very simple.. just an effect of perspective. You can find it well 
>explained in every book about meteor astronomy.
>Shortly, it's just like a long railroad: railroad is parallel, but it 
>seems to you that it radiates from one point far on the horizon.
>Similarly, orbits of the meteors of the same shower will be parallel to 
>each other, but they seem to radiate from one point in the sky, just 
>because their orbits are parallel.
>Nikola
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