[amsat-bb] Re: Dont loose the north
lucleblanc6 at videotron.ca
Fri Dec 28 16:17:35 PST 2007
Thank's for those who correct me The north star is in Ursa minor constellation
(not major) and for the half a degree or one error from the real north pole but
as stated we can live with it and i should wrote also to be able to confirm the
north with a GPS you should move away from your point towards Polaris this way
your GPS will show you a direction pointing to the star.
As my main topic was about not loosing the north... that's the minimum i can
wished you all in 2008. I am not too sure if wishing an Happy New Year is still
relevant? Should we wished us all a better new year instead? In french we
wished us good and happy new year (freely translated) a bit more realistic but
lets say the goals are the same only the means differs.
Here is some help to understand the North Star.
Today the Earth's axis points within one degree of Polaris, the brightest star
in the constellation Ursa Minor (also called the Little Bear or the Little
Dipper). Polaris appears to be in a fixed position in the sky throughout the
year. All other stars and constellations seem to revolve around the North Star.
In the case of the earth, precession is caused by the gravitational pull of the
sun and the moon. The earth's axis makes one complete rotation over the course
of approximately 26,000 years. If you trace the path of the axis in the sky,
you will find that Polaris, Vega, Thuban, and Alpha Cephei all fall on or very
close to it. So when the earth's axis is at a point on the path near Vega, Vega
becomes the North Star while Thuban is the North Star when the axis is near it
on the path.
Five thousand years ago, Thuban was the North Star. Five thousand years from
now, the North Star will be Alpha Cephei. Seven thousand years after that, it
will be Vega. Nine thousand years after that, Thuban will be the North Star
again. At these dates, the various stars will be at the closest to absolute
north. For some time before, the relevant star will be approaching due north
and it will be receding for some time after the time listed. In these interim
times, the North Star is whichever star is closest to north.
P.S. The North pole cap is melting too...just a reminder when you will give
your new year wishes! As i said don't loose the North ;)
Luc Leblanc VE2DWE
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