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From: cramer@kontron.UUCP (Clayton Cramer)
Newsgroups: net.space
Subject: Re: Red Sirius?
Message-ID: <622@kontron.UUCP>
Date: Tue, 18-Mar-86 15:46:34 EST
Article-I.D.: kontron.622
Posted: Tue Mar 18 15:46:34 1986
Date-Received: Mon, 31-Mar-86 04:17:33 EST
References: <860312-112018-1772@Xerox>
Organization: Kontron Electronics, Mt. View, CA
Lines: 29

> Why don't people go out and look at Sirius instead of arguing in a
> vacuum?  It turns out I often do (I mean look; the fact that I often
> argue is not the point :-), not to prove the "Red Sirius" theory, but
> because I like the stars.  Sirius almost always looks blue-white to me,
> but it has on occasion looked as red as a stop light.  It has also
> looked quite green, in fact within minutes of looking red.  These funny
> colors occurred when Sirius was low in the sky and the air was fairly
> turbulent.
> 
> While I must commend Firth for looking rather than blindly arguing, his
> observation of Venus instead of Sirius is probably irrelevant, because
> the finite size of planets (roughly a minute of arc for Venus) makes
> them behave differently than stars with regard to atmospheric effects;
> for example, planets twinkle decidedly less than stars.
> 
> After seeing Sirius quite red from atmospheric effects, I have to
> believe it simply got into the literature as red from such a viewing,
> and has been perpetuated in print.
> 
> /Don Lynn

But the ancients were quite knowledgeable naked eye astronomers.  They
would know that Sirius was, when low to the horizon, occasionally
red and other colors, for short periods of time.  Hard to believe that
they would call it "red" unless it was so quite consistently.

Also, the color distortions are because Sirius is low in the sky when
viewed from northern latitudes.  In the latitude of Egypt, it isn't
low in the sky.