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Location: UFOUpDatesList.Com > 2007 > Feb > Feb 26

Re: Natural Phenomenon? - Tarbell

From: Michael Tarbell <mtarbell.nul>
Date: Mon, 26 Feb 2007 09:33:02 -0700
Fwd Date: Mon, 26 Feb 2007 12:58:16 -0500
Subject: Re: Natural Phenomenon? - Tarbell


>From: Brian Callaghan <bjcallaghan.nul>
>To: ufoupdates.nul
>Date: Sun, 25 Feb 2007 12:16:52 -0500
>Subject: Natural Phenomenon?

>Does anyone have an explanation for stars that appear to flash
>or rotate green and red colours?

<snip>

Hi Brian,

This is probably what is known as scintillation.

From Minneart, The Nature Of Light And Color In The Open Air:

"The colour changes are to be ascribed to slight dispersion of
the normal terrestrial ray curvature, so that the rays from the
star travel along slightly different paths in the atmosphere,
according to their colour. For a star at a height of 10 degs.
above the horizon we compute distance between the violet and red
rays to be as much as 11 inches at a height of 1.25 miles, and
23 inches at 3 miles. The air striae are, on an average, fairly
small, so that it may often happen that the violet ray passes
through a striation and is deflected, whereas the red ray passes
on without deviation. The moments when the light of a star
becomes brighter or feebler as a result of scintillation are,
therefore, different for the different colours... Colour changes
never occur, apparently, at altitudes of more than 50 degs., but
frequently below 35 degs. The most beautiful scintillation of
all is that of the bright star Sirius, which is visible in the
winter months rather low in the sky."


Regards,

Mike




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