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Proof of the Earth's Rotundity



 
 
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  #21  
Old October 25th 14, 01:55 AM posted to sci.astro.amateur
Lord Vath
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Default Proof of the Earth's Rotundity

On Fri, 24 Oct 2014 20:54:37 +0100, "Lord Androcles"
wrote this crap:



"Bill Owen" wrote in message ...

On 10/23/14 12:43, Lord Androcles wrote:


"Quadibloc" wrote in message
...
You want astronomy to remain simply an inspirational pastime, with a
"thus far
and no further" to serious investigation of planetary motions. We would
never
have discovered Neptune listening to people like you.

John Savard

================================================== =============
Funny, I don't recall seeing "Savard" as a co-discoverer of Neptune in
any 1846 newspaper. Perhaps one need to be a pompous arsehole to belong
to "we".


Neptune would have been swept up by the Bonner Durchmusterung in the
1850s, although they might have mistaken it for a star. Certainly a
comparison of the BD to the plates of the Astrographic Catalogue
(difficult but not impossible in the 1890s) would have done the trick.
In other words, its discovery would have been like that of Uranus.

BTW, I can claim to be a co-discoverer of Neptune in a strange sort of
way. A few years ago I took a few exposures of Neptune (and Triton) and
submitted the astrometry to the Minor Planet Center along with all my
other asteroid observations that night -- and the MPC gave Neptune a
provisional designation! Gareth and I had a good chuckle about it, and
then he went off and upgraded the software so it wouldn't happen again.

-- Bill
================================================= ===
Why are planetary orbits so damned circular?


We only know about the ones around our star.

This signature is now the ultimate
power in the universe
  #22  
Old October 25th 14, 05:39 AM posted to sci.astro.amateur
oriel36[_2_]
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Posts: 8,478
Default Proof of the Earth's Rotundity

On Friday, October 24, 2014 11:37:26 PM UTC+1, Mike Collins wrote:


http://mars.nasa.gov/allaboutmars/nightsky/retrograde/


NASA assume that people are able to interpret images. The animations shows
Mars in the night sky from Gale Crater but to simplify the image they
didn't include the Sun or other visible planets assuming that interested
viewers would have the sense to realise this.


The Earth from the surface of Mars and its motion around the Sun would contain roughly the same features as Venus seen from Earth with its increase in size and its phases as it emerges out from behind the central Sun,swings out to its widest point and then back in front of the Sun

http://www.halien.com/TAS/Gallery/planet/Venus02.jpg

http://artsandstars.ens-lyon.fr/venu...es.png?lang=en

The trick is to account for the motion of the outer planet looking in towards the planet in an inner orbital circuit and that involves switching references to the motion of the background stars behind the Sun thereby setting up the central Sun as a reference point for the motion of the inner planet.

Try giving the NASA animation of the Earth seen from Mars the familiar increase in size as the Earth approaches the orbit of Mars or its phases and let me know how you get on.



  #23  
Old October 25th 14, 07:54 PM posted to sci.astro.amateur
Quadibloc
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Default Proof of the Earth's Rotundity

On Saturday, October 25, 2014 3:17:29 AM UTC-6, oriel36 wrote:

The one thing missing was what input the Earth's motion has in these sequence
of images as without the Earth's orbital motion, Venus would move through
those phases quicker from a stationary observer rather than being on a moving
Earth.


Yes, that's correct, since the Earth orbits the Sun in the same direction as
Venus, but (in angular terms) more slowly.

In eight years, there are five conjunctions between Venus and the Sun from
Earth's viewpoint, so the Earth catches up with Venus in its orbit five times.

Thus, from Earth, Venus is seen to go through its phases five times, while a
stationary observer would see it go through its phases thirteen times (5 + 8).

John Savard
  #24  
Old October 25th 14, 08:48 PM posted to sci.astro.amateur
palsing[_2_]
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Default Proof of the Earth's Rotundity

On Saturday, October 25, 2014 11:54:44 AM UTC-7, Quadibloc wrote:

... In eight years, there are five conjunctions between Venus and the Sun from
Earth's viewpoint, so the Earth catches up with Venus in its orbit five times.

Thus, from Earth, Venus is seen to go through its phases five times, while a
stationary observer would see it go through its phases thirteen times (5 + 8).

John Savard


Yes, and this graphic...

http://www.lunarplanner.com/Images/V...et%20Paths.gif

.... represents the path of Venus among the fixed stars over each of those 5 passages, the differences between them having to do with the position of Venus WRT the ecliptic, that is, if Venus is above the Sun or below the Sun or nearly even with the Sun as it arrives at inferior conjunction.

Alas, poor Gerald has no chance to understand, since he cannot visualize perspectives, even if his life depended on it... which, fortunately for Gerald, it doesn't...
  #25  
Old October 26th 14, 08:26 AM posted to sci.astro.amateur
oriel36[_2_]
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Default Proof of the Earth's Rotundity

On Saturday, October 25, 2014 8:48:59 PM UTC+1, palsing wrote:
On Saturday, October 25, 2014 11:54:44 AM UTC-7, Quadibloc wrote:

... In eight years, there are five conjunctions between Venus and the Sun from
Earth's viewpoint, so the Earth catches up with Venus in its orbit five times.

Thus, from Earth, Venus is seen to go through its phases five times, while a
stationary observer would see it go through its phases thirteen times (5 + 8).

John Savard


Yes, and this graphic...

http://www.lunarplanner.com/Images/V...et%20Paths.gif

... represents the path of Venus among the fixed stars over each of those 5 passages, the differences between them having to do with the position of Venus WRT the ecliptic, that is, if Venus is above the Sun or below the Sun or nearly even with the Sun as it arrives at inferior conjunction.

Alas, poor Gerald has no chance to understand, since he cannot visualize perspectives, even if his life depended on it... which, fortunately for Gerald, it doesn't...


What is encouraging is that people can put the increase in size of Venus and changes in phases as it approaches the Earth's orbit in context of its motion around the Sun so they should have no problem with the view of the Earth from Mars when its phases and increase in size will eventually be imaged..

http://www.farhorizons.nl/planets/Ve...007%20oost.jpg

There is no need to throw good information after bad so that Owen at JPL has the responsibility of setting his colleagues straight on how the motion of the Earth around the Sun and against the background stars would look like from the surface of Mars using the known principles based on the motion of Venus as seen from the Earth.

The input of the Earth's orbital motion into observations of the motion of the inner planets from the Earth's surface requires nimble reasoning as it requires a number of important modifications which chained older astronomers to observations which ultimately are counter-productive. The most notable modification is switching the reference for the Sun apparent motion through the background field of stars to the productive apparent motion of the background stars behind the central Sun thereby creating the background for appreciating the grandstand motion of the inner planets around the Sun.

Here is the less productive view of the Sun's motion through the Zodiac by Huygens and its nonsensical extension via Newton

" Here take notice, that the Sun or the Earth passes the 12 Zodiacal signs,or makes an entire revolution in the ecliptic in 365 days, 5 hours 49 min. or there about, and that those days, reckon'd from noon to noon, are of different lenghts; as is known to all that are vers'd in Astronomy" Huygens

"That the fixed stars being at rest, the periodic times of the five primary planets, and (whether of the sun about the earth, or) of the earth about the sun, are in the sesquiplicate proportion of their mean distances from the sun." Newton

Yes it is a tangle and yes most of it can be dealt with in a reasoned way so everyone can get a clear insight into where they stand without having to cut each other to pieces however,in the interim, people can appreciate the motion of Venus seen from Earth and safely predict what the motions of the Earth will look like from Mars.



 




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