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Kelper & Tycho - how did they come to their conclusions?
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Zubeneschamali wrote: »Not just to the Earth's motion, obviously you also have to consider Venus's own motion, which is more rapid than ours. But you have to consider the motion of Mars and Jupiter also: if they weren't moving, they would just wobble about in a parallax ellipse, not the track with retrogrades which we see.
Here's Venus:
Go back to the YouTube 'May's Planet Dance' and accompany the observed motion of Venus with the images containing the phases which show you how the planet moves around the Sun from our position as an outer planet. If someone else would be so kind as to post the YouTube graphic and the images together it would save a lot of typing as the next step is making it a rule how inner and outer planets differ when seen from an intermediate planet.
Thanks for keeping things cool as these type of threads are rare. Catch you in a few days.0 -
One of the reasons for a necessary affirmation by a number of people is that the partitioning of retrogrades in this manner is entirely new
Tell us, gkell, which monumental mind of modern astronomy came up with this concept which eluded Copernicus, Galileo and Kepler, as well as all the people who put together the Youtube clips you rely on to demonstrate it?
I think I can guess the answer, but I don't want to spoil everyone else's fun.0 -
I think I remember this user from previous very similar conversations with them. I see a demonstrated lack of desire to understand basic orbital concepts, with a tendency for putting forward "new" hypotheses by crackpots that are plain wrong and fail to stand up under scrutiny.0
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Zubeneschamali wrote: »Tell us, gkell, which monumental mind of modern astronomy came up with this concept which eluded Copernicus, Galileo and Kepler, as well as all the people who put together the Youtube clips you rely on to demonstrate it?
I think I can guess the answer, but I don't want to spoil everyone else's fun.
The Sky and Telescope YouTube graphic of Venus and Mercury over a month is important in that it is the only version I know that contains the Earth's orbital input via the apparent motion of ElNath,Castor and Pollux in sequence behind the Sun hence this perspective fixes the Sun as being central and allowing us the grandstand view of Mercury and Venus as they swing out from behind the Sun to their widest point and then swing back in front of the Sun as you showed in that graphic.
One of the reasons I needed an affirmation that inner planetary retrograde resolution cannot ignore phase changes is that it is entirely new hence separate perspectives are needed to partition inner and outer retrograde resolutions. A simple Google search using the string ' Mars retrograde' will show a NASA graphic showing what retrogrades of Mars will look like from the Earth in comparison to how the Earth will look like from Mars. It is,of course, disruptive fiction as the Earth will display phases and restrict observers in what they can do,at least in a good way.
So,anyone care to post that link 'Mars Retrograde' ?.0 -
So,anyone care to post that link 'Mars Retrograde' ?.
Getting bored now, but here's one more:
http://mars.nasa.gov/allaboutmars/nightsky/retrograde/
This is primary school stuff, and really nothing to do with Kepler.0 -
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Zubeneschamali wrote: »Getting bored now, but here's one more:
This is primary school stuff, and really nothing to do with Kepler.
The easiest way to tell that a planet is going around the Sun is by looking at its phases and the Earth will display the same set of phases when seen from Mars as Venus shows us from a moving Earth hence the NASA graphic is nonsense and demonstrates that observers in this forum are looking at the partitioning of retrograde resolutions as something new and exciting.
It is a journey readers are on so that if it is not possible to manage the observations and reasons behind the motion of the planets around the Sun as they appear to us on the surface of the Earth then discerning variable orbital speed further down that road on that journey can't be achieved and especially not the means how variable orbital speed can be proved over the course of a week.
The general rule is therefore that phases accompany retrogrades of the inner planets and I urge readers to go back to the Sky and Telescope graphic in order to figure out that as Venus and Mercury swing into and out from behind the central Sun to their widest points they move in the opposite direction to the background stars and while turning into the central Sun where Venus is always between ourselves and the Sun they the planet moves in the same direction as those stars hence retrogrades.
Sorry to see nobody can navigate their way through the images and what they dictate as it is a worthwhile challenge in meshing phases with our grandstand view of Venus and Mercury. Thanks for being considerate and producing the NASA graphic and its worthless view of what they think the Earth's orbital motion looks like from Mars however it should be second nature now to readers in this forum that phases will be present and therefore the Earth will appear like a closed loop as Venus does.0 -
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Zubeneschamali wrote: »aaand we're up to Galileo, 1610! How new can it get?
This is so exciting!
Where are you going to put the phases for the Earth in the NASA graphic which conjectures how the Earth would look like from Mars ?. I wouldn't bother as all it represents is a distraction and the whole point of the exercise is to move on to where variable orbital speed enters the discussion using the Earth's orbital input into the YouTube graphic where the stars move behind the Sun in sequence.
The only rule readers have to appreciate is that when looking at the inner planets from an outer planet are that phases mesh with the closed loop of retrogrades as the inner planets move from their widest point of their orbits seen from Earth and move either behind the Sun or in front of the Sun.
These facts are here to stay and sorry if you imagine that Earth will behave as the NASA graphic imagines as that shows no consideration for what actually happens. I thinks kids will love the true explanation up to this point even if adults have themselves to make the journey up to this point. I didn't get affirmation from two other readers in this forum so no grievances.0 -
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Zubeneschamali wrote: »I pasted in a link to the page earlier, but that page doesn't show anything about the phases of the Earth, it just shows a dot.
It doesn't matter at this stage, you are commended for always posting the images I requested with perhaps the YouTube images entitled 'Venus Transit 2012: Incredible Images Caught on NASA Satellite' showing the rare phase of a transit as Venus passes before our planet at the closest point in our common orbits around our parent star. For three to seven hours we glimpse one of the great wonders of astronomy as we have a grandstand view of a planets motion around its parent star while at all other times we use phases and size increase to infer the same thing.
The grandstand view of an inner planet's orbit does require an explanation as to where the Earth's orbital motion factors in hence the delicate means to set the central Sun as a reference by shifting the older perspective used by the original heliocentric astronomers in terms of the motion of the Sun through the background stars to the more productive apparent motion of the stars behind the stationary Sun. It is a challenge but one made easy with these new tools.
Retrogrades haven't been touched for 500 years since the illusion of the apparent backward motion of the outer planets were resolved by relative motions of a faster moving Earth so with today's tools it is possible to add something better by switching attention to inner retrogrades. It is an opportunity for present observers to working with imaging and tools that Copernicus and Kepler hadn't at their disposal and that is where I leave it.0 -
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So, six pages of distractions later, not a word on the OP's question, i.e. "HOW they made their discoveries... , the details of the experiments and measurements they took, and how they were done". Congrats on boring the pants off the rest of us though (well, ok, I can only speak for myself).It is an opportunity for present observers to working with imaging and tools that Copernicus and Kepler hadn't at their disposal and that is where I leave it.0 -
OP, here's a short intro to the different types of instruments, and a good article from 1978 about Tycho's instruments and their accuracy, with descriptions and diagrams.0
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So, six pages of distractions later, not a word on the OP's question, i.e. "HOW they made their discoveries... ,
Not from gkell, no, but I did link to a description of the geometry Kepler used to work out the size and shape of Mars orbit, given Tycho's measurements.0 -
So, six pages of distractions later, not a word on the OP's question, i.e. "HOW they made their discoveries... , the details of the experiments and measurements they took, and how they were done". Congrats on boring the pants off the rest of us though (well, ok, I can only speak for myself).
Considering that inner planetary retrogrades require a different set of references to resolve as we see Venus travel around the Sun with its phases basically announcing to everyone that we have a grandstand view of that spectacle, it is entirely up to observers as to whether they find this new approach boring or exciting.
It does require that the Earth's orbital motion is accounted for along with the apparent retrograde motion of Venus and Mercury and that is where it all differs from the original heliocentric astronomers. The observers in this forum are required to walk the path of observations used by those astronomers including how they distinguished the motion of the planets through the Zodiac from that of the Sun.
So,is everyone clear on the fact that we see Venus make a circuit of the Sun and there is no illusion involved as with the outer planets where they fall temporarily behind in view against the background stars .0 -
Zubeneschamali wrote: »Not from gkell, no, but I did link to a description of the geometry Kepler used to work out the size and shape of Mars orbit, given Tycho's measurements.
That is the usual junk, early on in the thread I posted Kepler's own words as to how he correlated the distance a planet is from the Sun using its orbital period -
But it is absolutely certain and exact that the ratio which exists between the periodic times of any two planets is precisely the ratio of the 3/2th power of the mean distances, i.e., of the spheres themselves; provided, however, that the arithmetic mean between both diameters of the elliptic orbit be slightly less than the longer diameter. And so if any one take the period, say, of the Earth, which is one year, and the period of Saturn, which is thirty years, and
extract the cube roots of this ratio and then square the ensuing ratio by squaring the cube roots, he will have as his numerical products the most just ratio of the distances of the Earth and Saturn from the sun.1 For the cube root of 1 is 1, and the square of it is 1; and the cube
root of 30 is greater than 3, and therefore the square of it is greater than 9. And Saturn, at its mean distance from the sun, is slightly higher than nine times the mean distance of the Earth from the sun." Kepler
In more formal terms -
"The proportion existing between the periodic times of any two planets is exactly the sesquiplicate proportion of the mean distances of the orbits, or as generally given,the squares of the periodic times are proportional to the cubes of the mean distances." Kepler
This contemporary fiction of using the Earth as a yardstick (AU) doesn't tally with Kepler's approach as he is not explaining elliptical geometry but merely equating periods with distance using relative orbital periods and distance. The astronomers may appear boring to the contemporary reader however they didn't have the ability to view motions over a longer term period into a visual form whereas that is easily done today and in some way this is what makes those men and their insights so spectacular just as Kepler himself noted -
". . . 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." 1596, Mysterium Cosmographicum
Pity that observers haven't understood sufficiently the founding principles for the Earth's motion between Venus and Mars and how retrogrades differ by perspectives or rather observers find the partitioning boring.0 -
That is the usual junk, early on in the thread I posted Kepler's own words as to how he correlated the distance a planet is from the Sun using its orbital period -
You keep quoting Kepler, Copernicus and Galileo stating their conclusions. Everyone already knows their conclusions.
The OP asked how did Kepler and Tycho come to their conclusions.
They did not come to them by eyeballing the retrograde motion of the planets in the sky, so all these graphics you like to watch are completely off the point.0 -
Zubeneschamali wrote: »They did not come to them by eyeballing the retrograde motion of the planets in the sky, so all these graphics you like to watch are completely off the point.
". . . 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." 1596, Mysterium Cosmographicum
It is not a matter of convincing you of the role retrograde plays in not only defining a planet as an object but also how all celestial objects were seen to move the background stars including the apparent motion of the Sun ,the idea was to get two others to affirm that inner planetary retrogrades and planetary phases go together to create a picture of planetary motion from a grandstand view.
The older perspective,based on the periodic times fails in this respect -
"Of all things visible, the highest is the heaven of the fixed stars. This, I see, is doubted by nobody. But the ancient philosophers wanted to arrange the planets in accordance with the duration of the revolutions. Their principle assumes that of objects moving equally fast, those farther away seem to travel more slowly, as is proved in Euclid’s Optics. The moon revolves in the shortest period of time because, in their opinion, it runs on the smallest circle as the nearest to the earth. The highest planet, on the other hand, is Saturn, which completes the biggest circuit in the longest time. Below it is Jupiter, followed by Mars.
With regard to Venus and Mercury, however, differences of opinion are found. For, these planets do not pass through every elongation from the sun, as the other planets do. Hence Venus and Mercury are located above the sun by some authorities, like Plato’s Timaeus (38 D), but below the sun by others, like Ptolemy (Syntaxis, IX, 1) and many of the modems. Al-Bitruji places Venus above the sun, and Mercury below it." Copernicus
So,until observers feel comfortable with the actual methods astronomers used to locate the Earth between Mercury and Venus it will not be possible to move on to variable planetary speeds. There are no 'hard sums', just an enjoyable journey through the history of astronomy using words of the original astronomers along with contemporary graphics,tools.
As readers here haven't expressed enthusiasm for the new approach to the inner planets and why they wander against the background stars using phases and size increase as a gauge there is nothing more I could or would do about it.0 -
Zubeneschamali wrote: »They did not come to them by eyeballing the retrograde motion of the planets in the sky, so all these graphics you like to watch are completely off the point.
". . . 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." 1596, Mysterium Cosmographicum
It is not a matter of convincing you of the role retrograde plays in not only defining a planet as an object but also how all celestial objects were seen to move against the background stars including the apparent motion of the Sun ,the idea was to get two others readers here to affirm that inner planetary retrogrades and planetary phases go together to create a picture of planetary motion from a grandstand view as opposed to the illusion created by relative motions in respect to the outer planets.
The older perspective,based on the periodic times fails in this respect -
"Of all things visible, the highest is the heaven of the fixed stars. This, I see, is doubted by nobody. But the ancient philosophers wanted to arrange the planets in accordance with the duration of the revolutions. Their principle assumes that of objects moving equally fast, those farther away seem to travel more slowly, as is proved in Euclid’s Optics. The moon revolves in the shortest period of time because, in their opinion, it runs on the smallest circle as the nearest to the earth. The highest planet, on the other hand, is Saturn, which completes the biggest circuit in the longest time. Below it is Jupiter, followed by Mars.
With regard to Venus and Mercury, however, differences of opinion are found. For, these planets do not pass through every elongation from the sun, as the other planets do. Hence Venus and Mercury are located above the sun by some authorities, like Plato’s Timaeus (38 D), but below the sun by others, like Ptolemy (Syntaxis, IX, 1) and many of the modems. Al-Bitruji places Venus above the sun, and Mercury below it." Copernicus
So,until observers feel comfortable with the actual methods astronomers used to locate the Earth between Mercury and Venus it will not be possible to move on to variable planetary speeds. There are no 'hard sums', just an enjoyable journey through the history of astronomy using words of the original astronomers along with contemporary graphics and imaging tools.
As readers here haven't expressed enthusiasm for the new approach to the inner planets and why they wander against the background stars using phases and size increase as a gauge there is nothing more I could or would do about it.0 -
As readers here haven't expressed enthusiasm for the new approach
The only thing you have proposed to explain which was of interest to anyone (and that was only me) was how you imagine you can show that orbital speeds vary according to position in a planet's orbit in a few minutes a day for a week using a watch and stopwatch.
At this stage, I think that you are worried that your proposed stopwatch exercise shows nothing of the sort, and you don't want to post it in case we shoot it down.0 -
Zubeneschamali wrote: »The only thing you have proposed to explain which was of interest to anyone (and that was only me) was how you imagine you can show that orbital speeds vary according to position in a planet's orbit in a few minutes a day for a week using a watch and stopwatch.
At this stage, I think that you are worried that your proposed stopwatch exercise shows nothing of the sort, and you don't want to post it in case we shoot it down.
You kindly posted the sequence of images of Venus showing its phase changes and the decrease in size due to that faster moving planet receding in the distance as it moves away from our planet while there are another sequence of images showing its mirror image as it emerges from behind the Sun and travels to its widest point before swinging back in front of the Sun. The completely dark phase known as a transit should be the next step as the time lapse footage of the inner planet overtakes our planet hence the grandstand view we have of Venus.
The explanation for the change in phases of Venus is even easier than the explanation for lunar phases as a means to explain the moon's motion around the Earth. so all that remains is the crucial step to account for the Earth's orbital motion when viewing Venus and that is where observed retrogrades come in.
No point in dwelling on that YouTube graphic you posted of Venus without phases and a ridiculous periodic looping motion it does not have, after all, phases and size increase control our observation of Venus. This is extended to the Earth as seen from Mars and here again I haven't seen the necessary affirmation that outer retrogrades differ from inner retrogrades by way of perspective changes seen from Earth.0 -
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Zubeneschamali wrote: »This from the guy who thinks he can explain retrogrades to the rest of us!!
What could be easier than the motion of Venus against the background stars as it travels behind the Sun from quadrature to quadrature and in the direction of the background stars when it travels in front of the Sun from our perspective. This is quite different to the outer planets which move backwards against the background stars as they fall behind in view just as slower moving cars fall behind in view in an outer lane when being passed by a faster car on an inner lane.
The general run of these things is a firewall of moderation but that is unnecessary as lack of enthusiasm generally kills a thread. I would imagine that kids will love the visual narrative that uses phases properly to promote the wonderful view we have of planetary motion however a more challenging additional perspective would be how the Earth's own orbital motion contributes to the picture.0 -
Have you considered that it's because it's completely off-topic for the thread? If you start a thread of your own you might well attract the following you desire.As readers here haven't expressed enthusiasm for the new approach to the inner planets and why they wander against the background stars using phases and size increase as a gauge there is nothing more I could or would do about it.0 -
Have to admit I lost that in the haze. Very useful, ta. I plan to follow the approach in Stellarium just to hone the practical skills. Combined with the information about Tycho's instrumental accuracy, I think it adds up to the answer to the OP's original questions.Zubeneschamali wrote: »Not from gkell, no, but I did link to a description of the geometry Kepler used to work out the size and shape of Mars orbit, given Tycho's measurements.0 -
Zubeneschamali wrote: »This from the guy who thinks he can explain retrogrades to the rest of us!!
http://www.popastro.com/images/planetary/observations/Venus-July%202010-January%202012.jpg
Now all you have to do is account for the Earth's orbital motion into those observations and there is no 'hard sums' involved. I suggest you return to the YouTube graphic which uses the motion of the background stars behind the Sun to arrive on the road where we can discuss variable orbital speed -
https://www.youtube.com/watch?v=MdFrE7hWj0A0 -
What could be easier than the motion of Venus against the background stars as it travels behind the Sun from quadrature to quadrature and in the direction of the background stars when it travels in front of the Sun from our perspective.
I take it all back, gkell, you do indeed have a new view of the retrogrades of the inner planets. It is utterly and laughably wrong, but it's definitely new!
Those "ridiculous periodic loops" ARE the retrogrades of Venus, they are the things you have been offering to explain for the past 6 pages. And you don't even know what they look like! Priceless!
http://www.davidcolarusso.com/astro/0 -
Zubeneschamali wrote: »I take it all back, gkell, you do indeed have a new view of the retrogrades of the inner planets. It is utterly and laughably wrong, but it's definitely new!
Those "ridiculous periodic loops" ARE the retrogrades of Venus, they are the things you have been offering to explain for the past 6 pages. And you don't even know what they look like! Priceless!
You posted a YouTube simulation of Venus with a meaningless retrograde loop heading off to nowhere whereas observers can enjoy the closed loop of Venus where phase changes along with variations in size keep the observer focused on the grandstand view of Venus as it circles the Sun -
http://www.masil-astro-imaging.com/SWI/UV%20montage%20flat.jpg
The external planets are a different matter as they display no phases while the retrograde loops signify a faster moving Earth overtaking those planets hence variations in the extent and duration of these retrogrades contain the reasons why orbital speeds vary rather than continue at a constant orbital speed -
http://apod.nasa.gov/apod/ap120809.html
http://apod.nasa.gov/apod/ap031216.html
No 'hard sums',just common sense and at least now I can post the graphic by Kepler which represents knowledge of variations in retrograde duration every time the Earth overtook Mars over a 16 year period indicating that planets orbital speed changes across an orbit -
https://upload.wikimedia.org/wikipedia/commons/e/e9/Kepler_Mars_retrograde.jpg
These visual narratives bring the insights of the old astronomers to life and alter their views when necessary however these are just small steps along the journey .0 -
You posted a YouTube simulation of Venus with a meaningless retrograde loop heading off to nowhere whereas observers can enjoy the closed loop of Venus
That "meaningless retrograde loop" is what we see when we look at the sky instead of Youtube. It is Venus in retrograde, which is what you are trying to explain, without even being able to recognize it when you see it.0 -
Zubeneschamali wrote: »That "meaningless retrograde loop" is what we see when we look at the sky instead of Youtube. It is Venus in retrograde, which is what you are trying to explain, without even being able to recognize it when you see it.
https://www.youtube.com/watch?v=_7U5VbasKr4
The pleasure in watching a planet move through space with the central Sun within the same picture whereas phase changes and increase in size is used to infer the grandstand view of motion around the Sun at other times and there are many such views of this type -
http://www.masil-astro-imaging.com/SWI/UV%20montage%20flat.jpg
So, quadrature to quadrature when Venus moves in front of the Sun the planet is in retrograde whereas quadrature to quadrature when Venus moves behind the Sun and the planet moves against background stars but both combined create a closed loop -
http://astrosnaps.co.uk/Venus-project-dark-x25.jpg
It takes an astronomer to enjoy the spectacle,after all,that is the whole purpose behind astronomy.0 -
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So, quadrature to quadrature when Venus moves in front of the Sun the planet is in retrograde whereas quadrature to quadrature when Venus moves behind the Sun and the planet moves against background stars but both combined create a closed loop
You are comically wrong. The synodic period of Venus is 584 days, of which it is in retrograde for only 41 days. If your lunatic notions were correct, Venus would be in retrograde half the time, instead of less than one tenth.
As for "quadrature", the term means when a body is at right angles to the direction of the Sun.
Venus and Mercury cannot reach quadrature seen from Earth.0
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