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Re: Jupiter's Great Red Spot

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In article <esqdnb_Sa6rvVPDEnZ2dnUU7-UfNnZ2d@earthlink.com>,
David DeLaney  <dbd@vic.com> wrote:
>On 2017-07-11, Greg Goss <gossg@gossg.org> wrote:
>> djheydt@kithrup.com (Dorothy J Heydt) wrote:
>>>As for the colors of planets (as seen through atmosphrere from
>>>Earth, mind you), 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.  If ever I
>>>meet an astrophysicist, I'll ask him/her, "What's your
>>>hypothesis," and if the answer is "I haven't got one," I'll take
>>>that as an honest answer.
>>
>> Three red objects?  How about Antares ("not Mars") and Betelguese?
>
>Astrophysics does have a hypothesis to cover that: namely, that in historical
>times Sirius B was a red giant, that there was a nova (which doesn't seem to
>have been recorded, but historical astronomy records are spotty in places),
>which led to it becoming the white dwarf we currently see.

But what about the big blue supergiant that we now see?
>
>Would require fairly coincidental timing, but we already know we had that with
>nearby _super_novae, a drought of which lasted from juuuust before the
>invention of the telescope (Kepler's, 1604) to a few decades ago when SN1987A
>popped in the Large Magellanic Cloud (and also showed up through neutrino
>astronomy). So not actually impossible.

Coincidences do happen.  I can see a supernova happening *just*
long enough ago that its light shines on Earth and fades out
*just* before anybody has a telescope.  But what about the big
blue supergiant?

I don't know nearly enough about star formation.  What is a
protostar befor it turns into a blue supergiant?  If one of those
were sitting in a big dust cloud, would the light reaching Earth 
look red?

Is there an astrophysicist in the house?

-- 
Dorothy J. Heydt
Vallejo, California
djheydt at gmail dot com

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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

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