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  #16  
Old March 8th 18, 07:26 PM posted to sci.astro.amateur
Bill[_9_]
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Posts: 311
Default Polar astronomy

On Thu, 8 Mar 2018 09:00:57 -0800 (PST), wrote:

On Thursday, March 8, 2018 at 4:39:48 PM UTC, Quadibloc wrote:
So I give Oriel a much better score than 100% wrong; to me he seems to be
very nearly right, even if some subtle distinctions apply.


The distinctions are not subtle.

How long does it take Io to go from "Left of Jupiter" (as Gerald would say) to "Right of Jupiter" and back to "Left of Jupiter" ? Galileo estimated it as 42.5 hours. This is so tiny compared to the orbit of either the Earth or Sun that it is effectively the same as the period of Io's orbit around Jupiter. By contrast, Venus orbits the Sun in 224 days, but does not return to its greatest Eastern elongation for 584 days because of the Earth's orbital motion.

Io is in retrograde for very close to half of each orbit of Jupiter, Venus for about 42 days of those 584 or 7% of the time.

Gerald continually posts a photomontage of the phases of Venus around a central Sun (without background stars or dates) and pretends that this represents something or other we might observe in the sky. It is baloney. Since he has never in his life actually looked at the sky and bases his ignorant rants on random youtube clips and jpgs, he knows no better, but you certainly do.


Agree.
I can't think of any professional level endeavor where that his sort of
lackadaisical, sloppy, piecemeal approach would provoke anything but
scorn from any audience.

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