Polar astronomy

On Tuesday, March 6, 2018 at 10:48:37 PM UTC, Bill wrote:

You don't need my participation for these "one-way" interactions of
yours.



It is perhaps a greater challenge to find common sense on Earth than life on Mars.

There was no sidestepping, the closest I am prepared to go to bridge the difference with the rest of the contributors in this newsgroup is to point out that the recent ability to condense long term imaging into recognizable motions at the scale of human experiences changes astronomy for the better. It belongs to the entire community who take the time to photograph topics like the actual loop of Venus using phases as a guide or the powerful Hubble telescope as it registers the dual surface rotations of Uranus.

I fully understand that the Scandinavian contributor in this thread knows exactly how, from a moving Earth, the illusory loop of the slower moving Mars differs from the actual loop of the faster moving Venus and that would bug him as Scandinavian people are wonderfully pragmatic and adaptive as I discovered from working there. I would counsel him to just teach the principle as it stands as no society that ever adopts a productive/creative view loses out while those societies who are prepared to live with falsehoods or deficient views do their populations no favors.

On Tue, 6 Mar 2018 22:08:27 -0800 (PST), Quadibloc
wrote:
The loops we see in Mars' apparent motion are illusory; Mars orbits
the Sun in an ellipse without loops.
Venus also orbits the Sun; the "loops" we see in its apparent
motion from Earth are that real orbit.

Not quite. The loops in the apparent motion of Venus relative to the
background of stars is smaller than the orbit of Venus. Which means
that the time period of the retrograde apparent motion of Venus is
considerably less than the time period from its greatest eastern
elongation to its greatest western elongation.

BTW the apparent retrograde motion of Mars, or of any other superior
planet, can be seen as a reflection of the orbital motion of the
Earth.

On Wednesday, March 7, 2018 at 6:08:31 AM UTC, Quadibloc wrote:
How can he be hilariously wrong... where he is exactly right?

You are hilariously wrong, too. Both Venus and Mercury show illusory closed loops against the background stars.

Watch the animation Dance of the Planets at http://www.nakedeyeplanets.com/movements.htm

The default position for cause and effect is the use of imaging or time lapse which refers the orbital motions of the planets (including our own) to each other or to the central and stationary Sun while gauging motions against the background stars is secondary.

As West/East are rotational orientation terms they give way to left (evening appearance) and right (morning appearance) of the Sun as comparing orbital motions like for like makes it easier to understand astronomical micro-events like the transit as Venus displays as it overtakes us and passes visibly in front of the Sun -

https://www.youtube.com/watch?v=_7U5VbasKr4


Analogous to the motion of Venus in its smaller and faster circuit around the Sun seen from a moving Earth are the satellites of Jupiter so no apparent/true motion is needed unless observers are entirely recalcitrant -

https://www.youtube.com/watch?v=FcrBAuLBXag


It is some progress to identify that the slower moving outer planets present a different perspective than the slower moving planets but obviously there will always be a minority who are attached to the 'fixed stars' framework or attached to defunct astronomical terms that are out of place in what should be the space age. For the faster moving Venus that framework disappears as the stars themselves transition from left/evening to right/morning due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=MdFrE7hWj0A

People in numerous organizations are just playing catch-up and that is fine but there is nothing really difficult in isolating the direct/retrogrades of Venus and Mercury while some observers in this newsgroup are the first to see how we see the faster moving planets from a slower moving Earth plays out.

Some additions and modifications.


* It is some progress to identify that the slower moving outer planets present a different perspective than the faster moving planets -

http://www.popastro.com/images/plane...ary%202012.jpg

VS

https://apod.nasa.gov/apod/ap011220.html


** When I said Scandinavian people are very good at adapting and recognizing fair play I should have said not all Norwegian/Swedish people but the vast majority are.

*** Good to see at least a semblance of an astronomical discussion for a change.

On Wednesday, March 7, 2018 at 2:50:45 AM UTC-7, Paul Schlyter wrote:

BTW the apparent retrograde motion of Mars, or of any other superior
planet, can be seen as a reflection of the orbital motion of the
Earth.

Yes. And the apparent retrogade motion of Venus... reflects the _real_
orbital motion of Venus. Because its overall average direct motion is what
reflects the orbital motion of the Earth.

That's the distinction Oriel was making, and it's a real distinction, even
if he garbled it a little.

John Savard

The back and forth motion of Venus gauged against the background stars as it processes an actual loop of the Sun displays the direct/retrogrades observed by astronomers since antiquity -

https://www.youtube.com/watch?v=MdFrE7hWj0A

The Earth's orbital motion only delays when Venus reaches its widest point from the Sun from our slower moving perspective so the bulk of the Earth's orbital motion is concentrated in the transition of the stars from left to right of the Sun or, as observers register it, the transition from an evening to morning appearance. This sets the Sun up as the central reference that it is for the actual loop of Venus and Mercury hence the analogy with Jupiter's satellites minus the glare we see with the Sun and the faster moving planes and their smaller orbital circumferences -

https://www.youtube.com/watch?v=FcrBAuLBXag


These are rare topics as they allow satisfaction without so much effort but they also provide intricate physical considerations for those who are more adventurous. Putting words in my mouth is one of the disadvantages of presenting new material on a newsgroup however the topic material is meant to be interesting enough to carry observers through jargon that diminishes the imaging and animations meant to convey an accurate narrative. All people are welcome to try their hand explaining these things but they must do so by their own efforts rather than trying to impose notions in my direction that I don't promote or present.

On Thursday, March 8, 2018 at 5:09:50 AM UTC, Quadibloc wrote:

And the apparent retrogade motion of Venus... reflects the _real_
orbital motion of Venus. Because its overall average direct motion is what
reflects the orbital motion of the Earth.

That's the distinction Oriel was making, and it's a real distinction, even
if he garbled it a little.

I understand what Gerald was saying, and it is not garbled, it is 100% wrong. He genuinely believes our view of Venus or Mercury relative to the Sun or to the background stars is like our view of Io and Europa relative to Jupiter. They go left, they go right, simple as. He is utterly wrong.

I do not understand the distinction you are making.

We see Io and Europa actually revolving around Jupiter, and we also
do see Venus and Mercury actually revolving around the Sun - even
though, in the latter case, our own motion is related to theirs, and Io
and Europa are carried along by Jupiter's mostly real motion and
Venus and Mercury are carried along by the Sun's strictly apparent motion.

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.

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.