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Mercury overtakes Jupiter
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02-01-2020 8:01am#1
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The Earth isn't travelling between them as it is on the opposite side of the Sun to both planets. It also has little to do with Mercury moving faster and Jupiter moving slower. If the planets involved were Mars and Jupiter they'd both appear to be moving the same direction with respect to the Sun, even though Mars would still be moving faster than Jupiter in space. In reality, the effect is an artifact of parallax from the moving Earth. If Earth were stationary with respect to the Sun then both Mercury and Jupiter would appear to move toward the Sun.https://sol24.net/data/html/SOHO/C3/96H/VIDEO/
Although it looks like Jupiter and Mercury are traveling in opposite directions, the perspective is created by the fact that the Earth is traveling between the faster moving Mercury and the slower moving Jupiter.
https://www.theplanetstoday.com/
Look at the SOHO time lapse. Note that the stars are drifting left to right across all three bodies, the Sun, Mercury and Jupiter. They are moving fastest across Mercury and slowest across Jupiter. Since the Sun ranks in the middle, Mercury and Jupiter must appear to be moving in opposite directions with respect to it. But if it were Mars instead of Mercury, the Sun would be moving fastest with respect to the stars, and both planets would be moving away from it.
To get an idea of how the parallax works we need a better solar system viewer, one which shows orbits to proper scale and shape. I recommend this one for better functionality. In particular it lets you export transparent pictures so you can overlay the planetary positions for different dates as I have done here:
I've blanked out all the planets except Earth (on the left), Mercury, and Jupiter (on the right). The planets are orbiting the Sun anticlockwise. The planet positions are shown for 29-Dec and 03-Jan (the same interval as the SOHO time lapse) in pink and black respectively. I have drawn lines extended through the Earth and Sun for the two dates, coloured the same way.
The line from Earth through the Sun is swinging around anticlockwise as time progresses (from pink to black). Both Mercury and Jupiter are moving in their orbits the same direction as that line. But Mercury's angular position as seen from Earth is changing faster than the line. Hence the black Mercury is closer to the black line than the pink Mercury is to the pink line. So Mercury appears to move toward the Sun, while Jupiter is falling ever further behind.
That's really all that needs to be said about it.0 -
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The Earth always travels between the faster moving Mercury and the slower moving Jupiter so scroll through the dates to affirm this -
https://www.theplanetstoday.com/
... The Earth may be the opposite side of the Sun yet it always moves between the faster moving and smaller circumference of Mercury and the slower moving and larger circumference of Jupiter.
The default view of your linked site shows circular orbits and nothing like the correct scale. It appears to be geared toward astrology. The radius of Jupiter's orbit is shown at around 1.6 AU instead of 5.2 AU. Nevertheless it does show that Earth's orbital radius is intermediate between those of Mercury and Jupiter, which is the only sense in which Earth is moving "between the circumference of Mercury and Jupiter". But we hardly even need diagrams to tell us that. It's true at all times. We've known it for nigh on 500 years. The specific current configuration is as I showed:
And by the way, to appreciate what's going on in detail you need more than a time lapse from SOHO. For instance, the Sun is moving around 1.1 degree per day against the background stars at present, compared to an average of less than one, as we are at perihelion. Mercury meanwhile is moving considerably less than its average angular speed, being near aphelion in an eccentric orbit. For these things you need a mathematical model, not just pretty pictures.
And we've known this for nigh on 500 years.The change in the position of the stars are an illusion created by the orbital motion of the Earth around the central/stationary Sun so it is the speeds of the individual planets and their relative speeds between them and to us which presents observers with more than a few combinations as they come into view and move different ways within the visual narrative.The first heliocentric astronomers didn't use the central Sun as a reference but used a 'fixed stars' background...
...This is all new and perhaps more objections will help move the issue out into the wider world.
...The eyes take a while to become accustomed to what is being played out in the time lapse but there is a point when people know what is where and how they move within the framework of a central Sun.
If you mean Copernicus couldn't see the planets when they were within a few degrees of the Sun, well that's a consequence of having a big fiery ball shining through an atmosphere. If you are saying that he would have been surprised to learn of the motions of the planets during conjunctions with the Sun, that's patently false (even though he thought the orbits were circular). Kepler, though, could have produced the above diagram to scale after the publication of the Rudolphine tables in 1627. So you could argue that this perspective is a little less than 400 years old. Still hardly new.
Yep, Kepler anticipated it in 1627, and Gassendi used it to spot a transit of Mercury four years later.It is not for everyone but for those who can, they can anticipate how the planets will be seen to move as they come and go when seen from a moving Earth and are entirely free to join in.0 -
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Listen, this is complete gibberish. You are quite simply, laughably wrong. You clearly don't know what a retrograde of an inferior planet is. You have been copying and pasting the same nonsense onto threads here for years. You do it on other forums too, for instance here.
Here are two images you constantly reference. You describe the first as "the illusory direct/retrograde loops of the slower moving planets" and the second as "the actual loops seen of the faster moving Mercury and Venus":
The second picture shows a complete orbit of an inferior planet. The inferior planets have retrograde loops just like the superior ones, but yours is not a picture of one. You don't appear to understand that. In similar vein you say that compared to the retrogrades of the superior planets: "the back and forth motions ( direct/retrograde motions) of Venus and Mercury require an entirely different framework". But the back and forth motions of the inferior planets between maximum elongations, behind and in front of the Sun, do not correspond to direct and retrograde motion.
Here is the next retrograde of Mercury coming up next month:
I have marked four events, clearly distinguishing the retrograde from the greatest elongations:- Feb 10 - greatest eastern elongation
- Feb 17 - begin retrograde motion
- Mar 10 - end retrograde motion
- Mar 24 - greatest western elongation
Retrograde motion of an inferior planet means exactly the same as it means for a superior one -- it reverses direction with respect to the fixed stars. It has literally nothing (nada, zilch) to do with "the sun as a fixed reference". It does happen to occur close to inferior conjunction so the Sun is in the picture, making it extremely difficult to observe. And far from "requiring an entirely different framework", a retrograde of an inferior planet and a retrograde of a superior planet are one and the same event, seen from different perspectives. For the absolutely most basic illustration, look at this animation:
https://www.desmos.com/calculator/llb0zzo6q2
When the superior planet is in retrograde from the perspective of the inferior planet, the converse is true at exactly the same time. However, the inferior planet is close to inferior conjunction, so difficult to see.
For a more lengthy video, see here:
If you don't get it after this spoon-feeding, I fear there is no hope for you.0 -
Here are two images you constantly reference. You describe the first as "the illusory direct/retrograde loops of the slower moving planets" and the second as "the actual loops seen of the faster moving Mercury and Venus":
The second picture shows a complete orbit of an inferior planet. The inferior planets have retrograde loops just like the superior ones, but yours is not a picture of one. You don't appear to understand that. In similar vein you say that compared to the retrogrades of the superior planets: "the back and forth motions ( direct/retrograde motions) of Venus and Mercury require an entirely different framework". But the back and forth motions of the inferior planets between maximum elongations, behind and in front of the Sun, do not correspond to direct and retrograde motion.
I don't mind your objections as I find it exceptionally useful in distinguishing the two different types of frameworks needed to account for the motions of the slower moving and faster moving planets seen from a moving Earth.
The major innovation is accounting for the Earth's orbital motion using the change in position of the stars from left to right and parallel to the orbital plane in order to set the Sun up as a stationary/central reference -
https://sol24.net/data/html/SOHO/C3/96H/VIDEO/
The faster moving Venus and Mercury run from right to left (direct motion in older terms) behind the Sun and from left to right (in retrograde motion) when the pass between the slower moving Earth and the central Sun. Their loops or circuits are therefore actual with some but very little influence in perspective due to the Earth's own orbital motion.
https://www.popastro.com/images/planetary/observations/Venus-July%202010-January%202012.jpg
The sequence of images took 18 months where everything to the left of the Sun is an evening appearance and everything to the right is a dawn appearance so the Earth's orbital motion only delayed when Venus reached its widest point as seen from Earth as both and evening or morning appearance. There is none of the relative speeds against a stationary 'fixed stars' background which were so important for resolving the direct/retrograde illusory loops of the slower moving planets seen from Earth -
https://apod.nasa.gov/apod/ap011220.html
The language of inferior/superior planets has passed its shelf life with space age travel as we can see the faster moving Earth from the slower moving Mars where the Earth too will be seen to move behind and in front of the Sun as a single actual loop just as we now see Venus and Mercury. Space age perspectives require space age people.
Observations presently are dominated by stellar circumpolar motion where the change in position of the stars from horizon to horizon is solely determined by rotation, however, the productive framework is the change in position of the stars from left to right thereby creating an anchor for perspectives using the true central/ stationary Sun. This modifies the older framework of Ptolemy where the Sun runs a course through a 'fixed stars' stationary background -
http://community.dur.ac.uk/john.lucey/users/sun_ecliptic.gif
Without the recognition that the stars change position using the central Sun as a central reference as a response to the Earth's orbital motion, none of this would make sense and none of the perspectives can be enjoyed.0 -
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The faster moving Venus and Mercury run from right to left (direct motion in older terms) behind the Sun and from left to right (in retrograde motion) when the pass between the slower moving Earth and the central Sun. Their loops or circuits are therefore actual with some but very little influence in perspective due to the Earth's own orbital motion.
And once again this is quite simply WRONG. If it were the case, the inferior planets would spend about half their orbits in direct motion and half in retrograde. They do not. The loop of an inferior planet around the Sun is a completely different thing to its retrograde loop with respect to the stars. A planet is NOT in retrograde throughout its passage from left to right in front of the Sun. No matter how many times you repeat this, it is fundamentally in error.
And so I give up. You can lead a horse to water but you can't make him drink. But nevertheless I will give you the wherewithal to confirm the facts visually for yourself. It's up to you whether you want to be like Galileo's dogmatic detractors and refuse to look through the telescope.
Launch Stellarium and follow these precise instructions:- Switch off the atmosphere and ground, and switch on an ecliptic grid.
- Search for and click on the Sun to keep it permanently centred.
- Zoom to about 50 degrees FOV.
- Advance the time in increments of one sidereal day, by clicking Alt '+'.
- You will see Mercury perform its orbital loops around the Sun.
- Set the date to 10-Feb-2020
- Click on θ-Aqr to centre it
- Now advance the time in increments of a sidereal day as before.
- You will see Mercury perform its retrograde loop, approximately centred on θ-Aqr.
- While this is happening, you will see the Sun zip across the view reflecting the the fact that an inferior planet's retrograde spans the time of inferior conjunction.
By the way, you will not be able to view the onset of Mercury's retrograde in your SOHO camera views. The LASCO C3 coronagraph has a field of view of only 30 solar radii, i.e. about 7 degrees either side of the Sun. Mercury will be twice that angular distance from the Sun in ecliptic longitude when it moves from direct to retrograde motion on Feb 17th. (Although in your mistaken terminology it will have been moving left-to-right in front of the Sun since Feb 10th).
It will come into view on SOHO around Feb 22nd at which point it will have dimmed to magnitude 3.6. This is not a problem as the coronagraph has a limiting magnitude of 7 to 8 (depending on Sun conditions). Indeed, this pass of Mercury takes it over 3 degrees of ecliptic latitude from the Sun so it remains partly illuminated and never gets above magnitude 5.3 at inferior conjunction, so it may remain visible for the whole duration. Mercury will still be in retrograde when it disappears off the right side of the coronagraph, so you also won't get to see it pass into direct motion while still travelling left-to-right w.r.t. the Sun.
Here's what would you would see if the coronagraph FOV was wide enough to encompass the entire orbit of Mercury. I hope you can understand it, but I won't hold my breath. After passing right-to-left behind the Sun, Mercury would stall and begin returning left-to-right (which you mistakenly call retrograde) but not as fast as the rightward drift of the stars. The planet's rightward speed would increase until after seven days it caught up to the stars and would be difficult to distinguish from the star field. It would then start to outpace the stars (i.e. actually in retrograde) until, having crossed the Sun it would slow down to star speed once more, thus ending its retrograde motion. Still travelling left-to-right it would now fall behind the stars, until eventually it also halted with respect to the Sun and tracked back right-to-left.0 -
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And once again this is quite simply WRONG. If it were the case, the inferior planets would spend about half their orbits in direct motion and half in retrograde. They do not. The loop of an inferior planet around the Sun is a completely different thing to its retrograde loop with respect to the stars. A planet is NOT in retrograde throughout its passage from left to right in front of the Sun. No matter how many times you repeat this, it is fundamentally in error.
And so I give up.
Actual observations from early September 2003 show Venus in direct motion as it travels behind the Sun and Mercury rocketing between the moving Earth and stationary central Sun in retrograde motion. The change in position of the background stars to the central Sun determines the Earth's orbital motion and speed but as Mercury travels faster than the Earth it moves quicker in respect to the stationary Sun, Mercury's motion to the background stars is also quicker hence observed retrograde motion -
https://www.youtube.com/watch?v=oQSmFbh64QQ&t=309s
The animated graphic helps observers put the whole September spectacle in perspective so it becomes a matter of normal judgments of motion which people are so good at when driving cars and extended to the celestial arena as long term and long range observations -
https://www.youtube.com/watch?v=-g5JkGzALNc
All this is an open door so it becomes a matter of who will work on this new project made possible by a satellite tracking with the orbital motion of the Earth. It has already been accepted to a large degree but because observers find it slightly difficult to change perspectives to a stationary Sun and the change in position of the stars arising from the orbital motion of the Earth, they are inclined to stumble.
Over the years, people sometimes try to insist that this is all known and even show a website outlining what I present here but unfortunately these websites insist in retaining the motion of the Sun through the constellations -
"The sun's direction in the sky, relative to the stars, keeps shifting to the left as the Earth and SOHO orbit around it."
https://www.sciencedaily.com/releases/2000/05/000508083145.htm
It shows why, since 2000, that the approach never gained acceptance, however, this can be fixed presently.0 -
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Funny thread. It’s like sitting in a quiet pub in the afternoon, reading a paper. The only other two people in the place are arguing over a topic you know a fair bit about. You can overhear that on of them is absolutely correct, and the other is demonstrating a perfect example of the Dunning-Kruger effect. You could join in, but you couldn’t be bothered because the one who’s right already knows it, and the one who’s wrong clearly ain’t for changing.
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Skill Magill wrote: »What happened in June 2011 that brought these planets together?
Check it out yourself as you see the faster moving Mercury overtake Venus with the central Sun as a reference around June 1st 2011 as both travel behind the Sun as seen from a slower moving Earth -
https://www.youtube.com/watch?v=aV-rCDHCh9U
There is no C3 camera footage for that date in June as the planets are out of range of the camera but later, Mercury can be seen continuing its path in direct motion around June 6th as it enters the time lapse and moving faster than the stars change position from left to right (due to the orbital motion of the Earth).
https://www.youtube.com/watch?v=mNXE6i3YZn8
Celestial sphere (RA/Dec) observers are inclined to talk about planets close to each other rather the more challenging solar system context which includes the Earth's orbital motion, fine if that is all observers can manage but not as satisfying.0 -
More of a teenager than an infant, I think. Stellarium's been able to do that since 2002. If you're not hung up on the animations, Kepler armed with his Rudolphine tables could have drawn it for you in 1627.This is a project in its infancy where the Earth's orbital motion is accounted for by the change in position of the stars from left to right of the central/stationary Sun... 0 -
More of a teenager than an infant, I think. Stellarium's been able to do that since 2002. If you're not hung up on the animations, Kepler armed with his Rudolphine tables could have drawn it for you in 1627.
Although I greatly admire the original heliocentric astronomers, I also feel dismay on their behalf as less careful people in the years after Galileo, Copernicus and Kepler butchered their methods and conclusions without the slightest feeling of shame.
https://upload.wikimedia.org/wikipedia/commons/e/e9/Kepler_Mars_retrograde.jpg
"Copernicus, by attributing a single annual motion to the earth,entirely rids the planets of these extremely intricate coils,leading the individual planets into their respective orbits,quite bare and very nearly circular. In the period of time shown in the diagram, Mars traverses one and the same orbit as many times as the 'garlands' you see looped towards the center, with one extra, making nine times, while at the same time the Earth repeats its circle sixteen times " Kepler Astronomia Nova 1609
The stationary 'fixed stars' background was the best these great astronomers could do as their observations were restricted to night time using a stationary background by which to gauge the motions of the planets . Nowadays the satellite can create permanent solar eclipse conditions where humans can peer at the central solar system and the background to allow observers to make sense of the central Sun using the change in position of the stars from left to right of the Sun thereby accounting for the Earth's orbital motion. From there it becomes a matter of making sense of the relationship of the planets to each other, why some brighten and darken or appear larger and smaller as seen from the moving Earth, how the galaxy appears from the orbital plane (it is just leaving the camera view presently) and many more facets to enjoy.
https://sol24.net/data/html/SOHO/C3/96H/VIDEO/
How difficult it was for astronomers in those times 400+ years ago yet they drew some of the finest conclusions without the advantages of today. In contrast, while any genuine observer can put the positions of the planets in context to the central Sun and to our orbital motion and position, very few have emerged to enjoy this new project.
Until, people recognise the proof/demonstration of the Earth's orbital motion is found in the change in position of the stars from left to right of the Sun, much of astronomy in structural context will not make sense.0 -
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The planetary phases prevent the faster moving Mercury and Venus anything other than actual loops with the Sun at the centre of their motions... It is impossible to render the motions of Mercury or Venus without the Sun at the centre and stationary to their motions so I wouldn't even bother trying. I have seen all sorts of silly attempts to explain the direct/retrogrades of Venus and Mercury but they fail for what should now be obvious reasons.
Quite simply wrong. This is what Mercury is going to do relative to the stars, beginning just over a month from now:
The circled star within the loop is Ancha (θ-Aqr). The crosses mark Mercury's position at approximately three day intervals, with the four numbered positions being: 10-Feb-2020, 16-Feb, 8-Mar, 27-Mar. At no time during this retrograde loop does Mercury reverse direction with respect to the Sun. The red crosses mark roughly the period during which Mercury will be visible in the SOHO/LASCO coronagraph, so the transitions between direct and retrograde won't be part of your "astronomical symphony".
Are you seriously claiming this is not going to happen? If you are not claiming that, in what way is it different from the "illusory loops" for the superior planets?
If they don't exist why did Ptolemy's model contain epicycles for Venus and Mercury? In any case, I've just done it. Now what?I won't even ask you to show the illusory loops of Venus and Mercury as seen from a slower moving Earth as they don't exist
Oh no, believe me, the pleasure is all mine. No need to demand.Again, I am not going to demand that you show me the illusory loops of Venus and Mercury because they just don't exist...
I'll bet you are!I am prepared to let this settle for a while...
Except, as I've clearly shown, your grainy little 15 degree aperture isn't wide enough to see the full retrograde loop of Mercury. Nevertheless, the entire thing will take place during Mercury's traversal in front of the Sun, and will involve no change of direction with respect to the Sun. Retrograde loops of the inferior planets always span inferior conjunction.... until Mercury and Venus come into view over the next number of months traveling in front and behind the Sun.0 -
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I just showed you that Mercury is about to make one of those illusory loops against the stars, quite separate from its actual loop around the Sun. You can believe it or disbelieve it, but just ignoring it makes you look obsessed. How about a one sentence answer for once -- do you accept that Mercury is going to perform an illusory retrograde loop against the stars next month or do you not?The illusory loops vs the actual loops of the faster and slower moving planets stand on their own...The illusory loops vs the actual loops of the The faster moving Venus and Mercury are [in] darkness at the centre of retrogrades as they pass between the stationary Sun and the slower moving Earth further out
Wrong again. As you presumably know, not every inferior conjunction is a transit which means an inferior planet can remain partly illuminated throughout its retrograde. At it's next inferior conjunction Mercury will pass almost four degrees above the ecliptic, leaving it 1% illuminated and at magnitude 5.3. Of course it will be too close to the Sun to have any chance of seeing it from Earth, but it means it won't disappear from SOHO's view.There are no illusory direct/retrograde loops of Venus and Mercury as phases representing orbital motion of those planets and the central Sun prohibit any such monstrosity regardless of what observers imagine otherwise.
You mean like this loop:
Sorry to burst your bubble but you better get used to it -- it's happening next month at a planet near you.I don't mind those who desperately are looking for an angle to maintain late 17th century Royal Society RA/Dec observing but such celestial sphere perspectives are only useful for predicting the times of astronomical events.
Sorry I had to use medieval software to prove you wrong. :pac:0 -
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If you tell students that Mercury is in retrograde whenever it is travelling left to right across the Sun, you are setting them up to fail -- hardly considerate....join a project to explain what is obvious is a clear and considerate way for students.
Mercury in retrograde around Ancha (θ-Aqr) from 17-Feb to 10-Mar-2020, but not throughout 10-Feb to 27-Mar between greatest elongations: 0 -
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You may want to play magnification hobbyist yourself for a moment. Compared to your favourite image of Venus's orbit, here is the field of view of the SOHO/LASCO C3 coronagraph. Do you really think this arrow slit provides the most complete perspective on planetary motion?Until Venus enters the C3 camera moving in retrograde motion between the stationary and central Sun and the slower moving Earth, observers here can ask themselves if they are astronomers or just magnification and identification hobbyists but in truth, all this is for people who can appreciate how satellite imaging completes a perspective where half has been missing.
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You may want to play magnification hobbyist yourself for a moment. Compared to your favourite image of Venus's orbit, here is the field of view of the SOHO/LASCO C3 coronagraph. Do you really think this arrow slit provides the most complete perspective on planetary motion?
You should be proud of your very Ulster Unionist like stance when it comes to protecting English RA/Dec modeling traditions but it comes at a price of all the other astronomical traditions that preceded the celestial sphere modeling and today where a satellite completes an astronomical picture from dawn to twilight in creating permanent solar eclipse conditions -
https://sol24.net/data/html/SOHO/C3/96H/VIDEO/
Your view this time around is interesting at least but when shown the actual speeds of planets within that observational corridor, observers can make sense of the motions of Mercury presently in respect to it motion to the central Sun, the slower moving Earth and the even slower moving Jupiter and Saturn.
I do know if you speak for the rest in this forum and I don't much care, the idea is that I can do these things because I simply can and students will love it. So, you have Venus go into direct/retrograde motion around a distant star and now you retreat to Venus in direct/retrograde motion around our central Sun over and extended period and that is just chasing an undisciplined person.
I suggest you keep that image when Venus comes into view within a number of months or I can borrow it for explaining how Venus moves between the stationary Sun and the slower moving Earth but also quicker than the change in position of the stars from left to right of the Sun.0 -
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