Venus phases and the eclipse

[Gerald Kelleher]

http://www.zam.fme.vutbr.cz/~druck/eclipse/Ecl1997r/Tse1997uw2/Hr/Tse1997uw2.png

http://www.popastro.com/images/planetary/observations/Venus-July%202010-January%202012.jpg

The images tell their own story of how we see the inner planets but the eclipse marks a singular moment in time when Venus and Mercury are not restricted to dawn or twilight appearances but are see as they truly are in relation to the Sun and to the Earth.

[Mark Storkamp]

In article <95fecfa0-1a16-4584...@googlegroups.com>,
Gerald Kelleher <kellehe...@gmail.com> wrote:

> http://www.zam.fme.vutbr.cz/~druck/eclipse/Ecl1997r/Tse1997uw2/Hr/Tse1997uw2.p
> ng
>
> http://www.popastro.com/images/planetary/observations/Venus-July%202010-Januar

> y%202012.jpg
>
> The images tell their own story of how we see the inner planets but the
> eclipse marks a singular moment in time when Venus and Mercury are not
> restricted to dawn or twilight appearances but are see as they truly are in
> relation to the Sun and to the Earth.

Are you implying that when we see Venus and Mercury during dawn or
twilight, they do not appear as they truly are in relation to the Sun
and to the Earth?

[Gerald Kelleher]

There is nothing to imply as everything is obvious even if it is entirely new. If not exactly paint-by-numbers, the astronomical procedure is straightforward for those who can follow the imaging and graphics

The circuits of Venus and Mercury seen from a slower moving Earth are simple loops where the planets move from left to right of the Sun with familiar phase changes and size increases as they approach the orbit of the Earth -

http://www.popastro.com/images/planetary/observations/Venus-July%202010-January%202012.jpg

The change in direction of the inner planets to the background stars including apparent retrograde motion is simply that the inner planets reach their widest point seen from Earth before moving in front of the central Sun, until they move to their opposite widest point before turning back in behind the central Sun.

https://apod.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

Factoring in the Earth's orbital motion doesn't require relative speeds which dominate the outer planets as they fall temporarily behind in view (retrograde motion) as the faster Earth overtakes them, the slower motion of the Earth supplies an entirely different set of references and inputs for the faster moving Venus and Mercury.

First and foremost, the Earth orbital motion sets the Sun up as an external reference and that is why you go to the eclipse image -

http://www.zam.fme.vutbr.cz/~druck/eclipse/Ecl1997r/Tse1997uw2/Hr/Tse1997uw2.png

The background stars also move from left to right behind the Sun as the Earth travels through space or, as we see it without an eclipse, from an evening appearance to a morning appearance depending on where the Earth is in its orbit. The minor orbital input of the Earth is the delay by which Mercury and Venus reach their widest points seen from Earth but otherwise the inner planets complete their loops as would be expected ,at least as seen from the 1997 eclipse image above.

The original heliocentric astronomers had to satisfy the antecedent geocentric data which included the observed motion of the Sun through the constellations rather than the new approach which has the stars move behind a central Sun (due,of course,to the Earth's orbital motion) -

". . . the ancient hypotheses clearly fail to account for certain important matters. For example, they do not comprehend the causes of the numbers, extents and durations of the retrogradations and of their agreeing so well with the position and mean motion of the sun. Copernicus alone gives an explanation to those things that provoke astonishment among other astronomers, thus destroying the source of astonishment, which lies in the ignorance of the causes." Kepler , 1596, Mysterium Cosmographicum

There are some decent but deficient explanations for outer planetary retrogrades but none whatsoever for the inner planets and with good reason, at least up until presently. Knowing how to stop the Sun from moving in order to allow the inner planets accomplish their observed loops is the key to partitioning an astronomical division that didn't happen until this century.

[Mark Storkamp]

In article <fafc7baa-bb69-4fc0...@googlegroups.com>,

Gerald Kelleher <kellehe...@gmail.com> wrote:

> On Wednesday, July 5, 2017 at 5:56:58 PM UTC+1, Mark Storkamp wrote:
> > In article <95fecfa0-1a16-4584...@googlegroups.com>,
> > Gerald Kelleher <kellehe...@gmail.com> wrote:
> >
> > > http://www.zam.fme.vutbr.cz/~druck/eclipse/Ecl1997r/Tse1997uw2/Hr/Tse1997u
> > > w2.p
> > > ng
> > >
> > > http://www.popastro.com/images/planetary/observations/Venus-July%202010-Ja
> > > nuar
> > > y%202012.jpg
> > >
> > > The images tell their own story of how we see the inner planets but the
> > > eclipse marks a singular moment in time when Venus and Mercury are not
> > > restricted to dawn or twilight appearances but are see as they truly are
> > > in
> > > relation to the Sun and to the Earth.
> >
> > Are you implying that when we see Venus and Mercury during dawn or
> > twilight, they do not appear as they truly are in relation to the Sun
> > and to the Earth?
>
> There is nothing to imply as everything is obvious even if it is entirely
> new. If not exactly paint-by-numbers, the astronomical procedure is
> straightforward for those who can follow the imaging and graphics
>

Then you're obviously wrong. But I won't bother explaining why since
it's straightforward for anyone who can follow a logical progression of
ideas and concepts.

[Gerald Kelleher]

Did nobody teach you a lesson - don't bring a knife (ideas and concepts) to a gunfight ( imaging and graphics).

We see the inner planets move around the Sun much like the satellites of Jupiter circle their parent and central planet -

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

The eclipse is special as the observation with the Sun at the center of the motions of the inner planets is absent due to its glare, only a rare planetary transit can match the event where a planet moves from left (evening) to right (morning) appearance is superseded when the Sun is in view -

https://www.youtube.com/watch?v=3X4FHiY-fJ4

[Quadibloc]

Maybe his phrasing was confusing.

But I think that his _point_ should be obvious.

Yes, whenever we see Venus or Mercury in the sky, except for atmospheric
refraction, we see them in their correct positions.

But the fact that they're usually obscured by the glare of the Sun or
the brightness of the daylight sky, so they are not visible except when
at a high value of elongation, does mean that we can't really see them
going around the Sun in as graphic or obvious a way as we can see, say,
the moons of Jupiter going around Jupiter.

Except for the fact that I've never heard of a solar eclipse that lasted
for an appreciable fraction of 88 days, I don't see how this particular
statement of his rests on any serious misconception of the Solar System.

John Savard