Newsgroups: sci.physics,sci.physics.relativity,rec.arts.sf.written,alt.astronomy Path: csiph.com!weretis.net!feeder6.news.weretis.net!feeder.usenetexpress.com!feeder1.iad1.usenetexpress.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!kithrup.com!djheydt From: djheydt@kithrup.com (Dorothy J Heydt) Subject: Re: Jupiter's Great Red Spot Message-ID: Date: Tue, 18 Jul 2017 14:07:38 GMT References: <595A82D3.1A46@ix.netcom.com> Organization: Kithrup Enterprises, Ld. X-Newsreader: trn 4.0-test77 (Sep 1, 2010) Lines: 44 Xref: csiph.com sci.physics:641208 sci.physics.relativity:425469 rec.arts.sf.written:475163 alt.astronomy:292196 In article , David DeLaney wrote: >On 2017-07-11, Greg Goss 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