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RE: (meteorobs) Re:Troy Simpson Fireball Obs.

Hello Graham,

Thankyou very much for your reply and your kind welcome and advice.
Just to quickly round up what you have told me, the object I saw in
Moura could well have been quite a lot further than what I perceived,
thankyou for clarifying that.  The thing I can't explain about the
object I saw in Brisbane was the lack of a sonic boom.  I am quite
certain of the close proximity of the object because of the clarity of
sparks and small firey ejections; I would expect that at 40 or 50 miles
those kinds of details would be lost in the brightness of the burnup.
Perhaps the object had already come below the speed of sound by the time
it was close enough for a boom to be audible?  Although it was still
moving fast, I guess it was losing so much mass that friction could do
its work much faster to slow the object than if it had still been large
and heavy.  I did perceive the object to come to a virtual standstill as
it came apart in it's final fiz of sparks.  Cheers!


Regards,

Troy Simpson


-----Original Message-----
From: Graham & Amy Palmer [mailto:gramy@globedot net.nz] 
Sent: Tuesday, 4 February 2003 5:56 AM
To: meteorobs@atmob.org
Subject: (meteorobs) Re:Troy Simpson Fireball Obs.


Hello Troy, welcome to the group. You are fortunate to have seen so many
beautiful objects. One thing that I noted from your observations is the
perception of distance... Usually most meteors (even the most
spectacular) burn up at around 100 - 70 kilometres (60 - 40 miles) above
the surface. However, due to the curve of the earth and surrounding
atmosphere, the objects can often appear as only just missing the
ground. (I have been tricked by this myself) If any object doing meteor
speeds got to within a few kilometres of the ground, there would be one
or more sonic booms, and going by what you say, these were not observed.
The colours you observed are due to the chemical composition of the
objects. Going by your description, it sounds like the second one was a
bit of old rocket casing or something similar. Such objects are notable
for their 'slow' motion across the sky, and long duration. Keep up the
observing but try to get used to measuring things like brightness
(magnitude), speed (scale of 1 - 5), and duration. Also try and note the
movement across background stars, this will help determine if what you
see is part of a shower, or a sporadic... Hope this is of some help,
Graham.

PS: On the subject of the Columbia tragedy, I was at a starparty in New
Zealand a few hours before the accident. I was treated to a nice view of
the orbiter through my telescope. So to hear of the news when I woke
next day, was just numbing. I still have trouble realising she is lost.
My sympathies go to all affected, and may her crew be honoured, by the
continuation of the space programme.


Graham Palmer
1/622 Nelson St. North,
Mahora.
Hastings, New Zealand.
Home phone: 06-8735951
Graham's cell No: 021-2650487

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