[amsat-bb] Re: Dont loose the north

Jim Towler jtowler at xtra.co.nz
Mon Dec 31 01:02:10 PST 2007


Yes, the stars follow a circular path: they just sit there, and the earth

Looking at all the straight lines, most have a flash at a regular spacing. I
expect those will all be aircraft. So, in the short time they take to cross
the field of view, the earth does not rotate any meaningful amount.
Interesting the ones with massive direction changes. I'd guess the location
is not far from an airport. Not at all a good spot for Astronomy really :-)


-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Andrew Rich
Sent: Monday, 31 December 2007 8:00 p.m.
To: Tom Clark, K3IO; AMSAT BB
Subject: [amsat-bb] Re: [SPAM] Re: Dont loose the north

Thats awesome - so stars follow a circular track, and other objects from a
line ?

Andrew Rich VK4TEC
vk4tec at people.net.au <mailto:vk4tec at people.net.au>

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org]On
Behalf Of Tom Clark, K3IO
Sent: Monday, 31 December 2007 4:02 PM
Subject: [SPAM] [amsat-bb] Re: Dont loose the north
Importance: Low

With all this discussion about Polaris, I thought you might find a
couple of photos I took back in 2002 that shows you that the earth's
spin axis is close to, but not precisely at Alpha UMi. Take a look at
http://www.pbase.com/tomcat/aurora. The right-hand picture
(http://www.pbase.com/tomcat/image/5186538)shows how the stars move over
about 4 hours. The star nearest the center of the arcs is Polaris; if it
was precisely at the pole, then the arc would have been a point.

You may also find the animated GIF photos of a (relatively) rare
low-latitude (Maryland) Aurora interesting.

73 & Happy New Year -- Tom

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