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Re: Jupiter's Great Red Spot

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Gary Harnagel wrote:

> On Tuesday, July 4, 2017 at 10:08:37 AM UTC-6, Thomas 'PointedEars' Lahn
> wrote:

Attribution _line_, not attribution novel.

>> Dorothy J Heydt [wrote]:
>> > […] there used to be a saying among classic (I mean Greco-Roman times),
>> > that three astronomical objects shone red: Sirius, Mars, and Jupiter
>> > (but not as red)  Sirius is certainly not red today, and current
>> > astrophysics has no explanation for a star turning from bright red to
>> > bright blue-white.  […]
>> 
>> Yes, it has.  For example, there is the Asymptotic Giant Branch (AGB)
>> where a *red* giant becomes a *white* dwarf
> 
> But it's supposed to take about 100000 years to go from red giant to
> white dwarf, not 2000 years.

From where did you get this figure?

We do not know where Sirius (which is actually a binary star system) came 
from, and what the mass of the original star was.
 
>> (a blue tinge can also be caused by Terra’s atmosphere).
> 
> And red, too, as anyone who looks at Sirius will note.

Maybe to some people in some locations when it rises or sets.  I have never 
observed Sirius to appear red[dish] from Central Europe, not even when it 
was rising.

It matters how long the path through the atmosphere is, and what the 
atmospheric conditions are (e.g. air pollution), as Rayleigh scattering by 
air molecules and particles scatters light of shorter wavelengths (e.g. 
blueish light) more than that of greater wavelengths (i.e. reddish light).  
Thus, the longer the atmospheric path, the more reddish does the light 
appear (see also: sunrise/sunset, lunar eclipse, and blood/harvest moon).  

This is actually given as one of the more likely explanations for the color 
discrepancy: ancient astronomers whose reports this “saying” was based on 
looked at Sirius at a different angle.

See also: <https://en.wikipedia.org/wiki/Sirius#Colour_controversy>

> But how come Antares doesn't show blue tinge?

Because of what I explained before, a star that is emitting white light 
(i.e. equally on all wavelengths of the visible spectrum) can easily appear 
blue-white when its light passes on a short path through an Terranish 
atmosphere.  That is not so easy with a star that is mostly emitting red 
light (emission maximum towards the red end of the visible spectrum).

<https://en.wikipedia.org/wiki/Rayleigh_scattering>

F’up2 sci.astro *again* (this has *nothing* to do with relativity, little 
with physics)

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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Jupiter's Great Red Spot  The Starmaker <starmaker@ix.netcom.com> - 2017-07-03 10:45 -0700
  Re: Jupiter's Great Red Spot Whisper <beaver999@ozemail.com> - 2017-07-04 21:22 +1000
    Re: Jupiter's Great Red Spot Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-07-04 15:03 +0200
    Re: Jupiter's Great Red Spot djheydt@kithrup.com (Dorothy J Heydt) - 2017-07-04 14:25 +0000
      Re: Jupiter's Great Red Spot Gary Harnagel <hitlong@yahoo.com> - 2017-07-04 09:03 -0700
        Re: Jupiter's Great Red Spot Upech Bezradne <adeeia@bbzzeop.ic> - 2017-07-07 10:45 +0000
          Re: Jupiter's Great Red Spot Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-07 09:20 -0500
            Re: Jupiter's Great Red Spot Ursler Zilberschlag <ursler@zilbersch.org> - 2017-07-09 09:39 +0000
      Re: Jupiter's Great Red Spot Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-07-04 18:08 +0200
        Re: Jupiter's Great Red Spot Gary Harnagel <hitlong@yahoo.com> - 2017-07-04 11:05 -0700
          Re: Jupiter's Great Red Spot Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-07-05 01:24 +0200
            Re: Jupiter's Great Red Spot Gary Harnagel <hitlong@yahoo.com> - 2017-07-04 18:46 -0700
              Re: Jupiter's Great Red Spot Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-07-05 04:48 +0200
                Re: Jupiter's Great Red Spot Gary Harnagel <hitlong@yahoo.com> - 2017-07-04 20:44 -0700
      Re: Jupiter's Great Red Spot Greg Goss <gossg@gossg.org> - 2017-07-11 07:08 -0600
        Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-13 08:50 -0700
          Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-15 11:19 -0700
            Re: Jupiter's Great Red Spot Garfield Dieter <igdle@rdlge.rf> - 2017-07-15 18:23 +0000
              Re: Jupiter's Great Red Spot Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-07-17 22:53 +0200
            Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-15 12:35 -0700
              Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-15 12:49 -0700
                Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-15 14:23 -0700
                Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-15 14:35 -0700
                Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-16 13:03 -0700
                Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-16 17:11 -0700
                Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-19 10:12 -0700
                Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-19 10:18 -0700
        Re: Jupiter's Great Red Spot David DeLaney <daviddelaney@earthlink.net> - 2017-07-18 03:40 -0500
          Re: Jupiter's Great Red Spot djheydt@kithrup.com (Dorothy J Heydt) - 2017-07-18 14:07 +0000
            Re: Jupiter's Great Red Spot Robert Woodward <robertaw@drizzle.com> - 2017-07-18 09:02 -0700
            Re: Jupiter's Great Red Spot David DeLaney <daviddelaney@earthlink.net> - 2017-07-18 14:13 -0500
    Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-04 12:13 -0700
      Re: Jupiter's Great Red Spot Whisper <beaver999@ozemail.com> - 2017-07-05 19:29 +1000
        Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-05 11:39 -0700
          Re: Jupiter's Great Red Spot The Starmaker <starmaker@ix.netcom.com> - 2017-07-08 12:22 -0700
  Re: Jupiter's Great Red Spot  Hägar <hsahm@yahoo.com> - 2017-07-04 08:31 -0700

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