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(meteorobs) Distance for simultaneous meteor observation
Phillip Tattum wrote:
>
> And have a question I'm sure you will be able to help me with!
> If I see a meteor, what sort of distance will it be visibe over? - I mean if
> I see it here in London, would someone in say Paris be able to see it too?
> Best wishes and enjoy Y2K
> Phillip
I have noticed this question come up several times before, so here is
the precise answer to this query:
To find the maximum distance apart two observers could see the same
meteor, you first need to find at what distance the furthest meteor can
possibly be seen away from you is. (Which is also the radius over which
the given meteor will be visible over) The maximum possible distance
between the 2 observers observing the same meteor will then be twice
this.
So, if we define:
d = distance from observer to meteor sub-earth point (which is the point
on the earth directly below the meteor). (d is measured along the earth
surface in km)
A = altitude of meteor as seen by observer (degrees).
h = height of meteor above the earth surface (km).
R = radius of the earth (km).
we get:
d = (pi/180) * R * [ARCCOS(COS(A)/(1+h/R)) - A]
so, using R=6367km, h=50km for an average meteor, the formula becomes:
d (km) = 111 * [ARCCOS(0.9922*COS(A)) - A]
Therefore, the most distant meteor visible to the observer would appear
at an altitude of 0 deg (theoretically), which corresponds to d =
111*[ARCCOS(0.9922*COS(0))-0] = 795km.
So, in theory, 2 observers separated by 2*795 = 1590km could see the
same meteor. However, it is impossible to see a meteor at zero altitude
due to atmospheric extinction. The lowest altitude a meteor is visible
will depend on many factors, including the brightness of the meteor and
the atmospheric conditions along its visible path. But, lets say a
bright meteor could easily be seen at an altitude of 5 deg, then the
formula shows d = 111*[ARCCOS(0.9922*COS(5))-5] = 414km.
So, 2 observers 828km apart could both see this meteor at an altitude of
5 deg, assuming it travelled in a path directly half way between the 2
observers.
I dont know how far Paris and London are apart, but I would very roughly
guess that 1000km is the maximum realistic distance 2 observers apart
could see the same meteor (at an altitude less than 4 deg!), under
pretty ideal circumstances.
I hope this answers your question! Sorry for the lengthy response, but
what else to do on a slow holiday weekend, but derive formulas?
Cheers and Happy New Years!
Mike
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