The Great Comet of 1680

Discussing all things related to the sighting of the comet in 1680 and its long term effects on the development of modern science.

Hi All,
I started this thread really for my own benefit so I could get more of an understanding of the 1680 comet as it is a critical inflection point in the development of modern science.

So I downloaded Principia first of all so I could see the data used by Newton to plot the path of the comet. There’s a lot of interesting stuff in there on the comet.

The first three observations that Newton uses are those made by Gottfried Kirsch as referred to by Simon in the Tychos book. Let me now quote from page 479 of the Principia

“The comet also appeared in the November before, and at Coburg, in Saxony, was observed by Mr. Gottfried Krich, on the 4th of that month, on the 6th and the 11th O.S; from its positions to the nearest fixed stars observed with sufficient accuracy, sometimes with a two feet, and sometimes with a ten feet telescope; from the difference of longitudes of Coburg and London, 11 degrees; and from the places of the fixed stars observed by Mr. Pound, Dr. Halley has determined the places of the comet as follows:- … the first observation from the position of the comet with respect to certain small fixed stars had all the exactness that could be desired; the second also was accurate enough. In the third observation, which was the least accurate, there might be an error of 6 or 7 minutes [or 60 perhaps - stateless comment?] but hardly greater.”

Newton includes all three observations in his calculation for the orbit of the comet. But notice how the data he includes is not the observed data but the data calculated by Halley for where the comet should have been a day before based on that observed data. So the object is observed by Kirsch on the 4th, 6th, and 11th of November but the data used by Newton is CALCULATED by Halley for the 3rd, 5th, and 10th of November. At least that is the impression I get from reading from the bottom of page 478. These dates are in Julian time so you need to add 10 days to get the current date.

Newton also omits the data he has collected from various sources from the middle to the end of November which is interesting. He states it is too imprecise.

Anyone below I have included a comparison of the eros RA and Dec I pulled from the JPL database compared to that for the Comet 1680 for the beginning of November 1680.

Given the inaccuracy admitted by Newton in the last measurement and the fact the values are calculated, there is a margin for quite a significant amount of error. I am definitely convinced that Newton is using the Eros data here and making a momentous error though I suspect Hadley is the man pulling the strings here.

It seems blindingly obvious to me that they manipulated Kirsch’s data in November to get a better fit for their parabola. It’s also clear that Newton’s theory works just as well with parabolas as it does for ellipses so why not for any other shape you care to think of?

Anyone below I also include the data I took for the comet 1680 from the JPL database using the dates and times given by Newton on page 480 of Principia. I find it useful for just plugging into Google Sky to get an idea of where it supposedly was on what day etc.

Btw what is the best tool to use for looking up objects in the sky? I downloaded the Google app but is there something better?

Dear stateless,

For the benefit of our readers I feel compelled to illustrate in the simplest possible manner what I discovered with regards to the all-important “Great Comet of 1680” episode which evidently fooled Isaac Newton and Edmond Halley’s into reaching their (spurious and illusory) conclusions - i.e that comets revolve around extremely elongated, cigar-shaped orbits…

So here’s a concise summary of the unfortunate and fortuitous chain of events responsible for this momentous and regrettable mix-up that effectively messed up the entire course of science & astrophysics.

On November 14, 1680 the German astronomer Gottfried Kirch announced that he had observed a bright new body in the sky which he believed (but wasn’t quite sure) was a comet. Here’s an extract from a paper titled “First discovery of the Great Comet of 1680”:

”Kirch noticed the comet first at Coburg, early on the morning of the 14th of November, 1680, and seems to have felt a natural pride at being the first to detect a comet with the assistance of a telescope before it had been seen with the naked eye. It was, at the time, not far from the planet Mars, and was just visible to the naked eye. At first, he doubted whether it was a new comet, or a nebula similar to that in the girdle of Andromeda; but its motion soon decided that it was the former.” “First discovery of the great comet of 1680” - by W.T. Lynn (1888)

Well, as I have illustrated in my book, what Kirch saw was NOT a comet - but the yet-to-be-discovered asteroid Eros which, on November 14, 1680, was in fact transiting not far from Mars (as viewed from Earth) at about 10h of RA. This also ‘happens’ to be just where the “Great Comet of 1680” was supposed to transit on that very same day (according to the NASA/JPL simulator) !

Eros however, soon disappeared from view.

Then, in late December 1680, a large comet (reputedly “one of the brightest comets of the 17th century” ) with an impressive tail suddenly appeared at the opposite side of our planet. As shown by the Tychosium simulator, this was none other than Halley’s comet (please know that the “Great Comet of 1680” is not reckoned to be returning anytime soon. Wikipedia says: “JPL Horizons shows the comet has roughly a barycentric orbital period of 10000 years”…). How convenient! We don’t need to worry about the return of the “Great Comet of 1680” - for another 10000 years or so!

So, to recap this chain of events - as they most likely unfolded IN REALITY:

  • On November 14, 1680 asteroid Eros was mistakenly identified as a comet - approaching “above the Earth” (at about 10h of RA).

  • In late December 1680, a huge comet with a long tail suddenly appeared “below the Earth” (at about 22h of RA).

The two sightings were interpreted by Newton and Halley as being the very same object. With this (spurious) idea in mind, they calculated the apparent trajectory of this “same object” - and concluded that it must have made a sharp U-turn around the Earth. And this led to their patently absurd conclusion that cometary orbits revolve around cigar-shaped orbits, unlike ANY other celestial bodies in our skies !,

I would strongly encourage all forum members interested in Halley’s comet to read the longest chapter in my book titled “Halley’s comet - the Great Deceiver”. I believe that it provides the ultimate, definitive and incontrovertible proof of the correctness of the TYCHOS model.


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Hi Simon,
The reason I was looking at this is to try and find out exactly what Newton and Halley were doing. Newton calculated the comet’s trajectory initially on something he observed personally from the 7th of March until the 19th of March 1681. Here he was tracking something moving through Perseus which he believed was a new comet. Below is an image of the diagram he uses in Principia to illustrate the path of the comet on page 475.


Below is what I am certain this diagram is referring to and shows the position of the ‘comet’ on March 11, 1681. A in Newton’s diagram is Per Omicron, B is Per Zeta and C is 42 Per in Perseus. As you can see the ‘comet’ is at RH 03 47 41.17 +32 48 23.7


On this day according to the Tychos, Halley’s comet is at RH 22h 55m 39s +00°28’44" so he is most definitely not observing this. So my simple question is - What is he observing?

It doesn’t look to me as if there is any table in Principia relating to the comet’s motion that isn’t a result of observation and manipulation by Halley. Halley calculated the final table on p 480 assuming what had been observed must have been the same comet that had supposedly returned four times with a period of 575 years previously. That’s science for you!

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That’s a great question, dear stateless - but I’m afraid I have no answer for what that object he claimed to have seen on March 11 1681 might possibly have been. On that date though, the JPL/NASA simulator indeed has “Comet 1680 V1” transiting at RA 3h 47m and DECL +32° 48’.

But having spent some time these last few days consulting the JPL simulator, I am compelled to quote an expression coined by poet George Villiers in 1671: “the plot thickens!”.

You see, by all accounts the “Great Comet of 1680” was viewed with the naked eye by a great many people in late December 1680, steeply descending towards their (European) horizons. It later disappeared from view in early February 1681. This would all seem to be consistent with how Halley’s comet would have ‘behaved’ according to the Tychosium simulator: it is seen steeply descending in late December 1680, and would then have disappeared behind the Sun in early February. We also have accounts of when it first appeared in that part of the sky, i.e. December 15.

To be sure, the Wikipedia page for “the Great Comet of 1680” features various depictions of the comet’s descending path such as this commemorative medal, a screenshot from the Stellarium simulator and even a famous painting of the event:

As you can see in my below screenshot from the Tychosium simulator, this would seem to agree with the descending path of Halley’s Comet on the date 1680-12-29, when it transited at about 22h of RA and -0.3° of DECL (which nicely ‘checks out’ with the Stellarium’s longitude for the “Great Comet of 1680” - at about 22h of RA, right beneath the Delphinus star cluster). Note that my yellow man’s plane should probably be even more tilted than that. All in all, the Tychosium is in very good agreement with the ephemerides and trajectory / descending path documented in the history books for the “Great Comet of 1680” (in December):

Now, here’s where the “plot thickens”. On December 29, 1680, the JPL/NASA simulator has “C/1680 V1” (The “Great Comet of 1680”) at RA 19h49m and DECL -03°08’, i.e. about two hours “off” in RA (wrt to the Tychosium) - yet fairly close to the DECL of -0.3°55’ in the Tychosium.

But as we look at a sideview of the JPL simulator, the comet clearly appears to be ascending ! It is truly unfathomable how this could possibly portray that steeply descending path observed in Europe in 1680 :

As for that hilarious claim by Edmond Halley (that he was somehow able to calculate a 575-year period for the “Great Comet of 1680”), it only goes to show the sheer arrogance of the man - for how on Earth could he possibly have had the pretense to have worked out any sort of period on the basis of a brief, single passage of a “never-seen-before” comet? As you rightly say: “That’s science for you!” :roll_eyes: (by the way, the current / modern estimated period for the “Great Comet of 1680” - which ‘just happened’ to occur only a year or so before Halley’s comet’s 1682 passage - is now something like 10000 years!..)

In conclusion, I rest my case: the so-called “Great Comet of 1680” (a.k.a. “Newton’s Comet”) was simply a misidentified sighting of none other than what later became known as the famous “Halley’s comet”. Yet, it was used by Isaac Newton to construct his hallowed cometary theory - and was even acclaimed as a definitive confirmation of his sacrosanct ‘laws’ of gravitation !

i will be the first to sugjest that we call it “Shacks Comet of 2023” for the obvious reason that you have finally discovered its true orbit. :dizzy: :kissing_heart:

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Hi Simon,
The section on the Great Comet in Principia reads more like a student project than real science. It’s extraordinary how they got away with this in retrospect. I’m now absolutely convinced Newton’s laws of celestial mechanics are utter BS, especially as Halley has admirably demonstrated you can fit any observed data to any kind of parabola or ellipse you wish! Just a tweak here and a tweak there and a few ginormous assumptions later you’ve constructed a new universe out of a few equations.

By the way on the JPL site they do have this notice which you’ve probably seen.

Clearly, the RA/Dec data that you can get from the Horizons system is the ‘source’ of truth and you need to be careful with this viewer. In fact, Mr. Shack, I realise you are a busy man, but could you just check one thing for me? I’ve been looking at the passage of Halley’s comet in 1759 on the JPL simulator and it just doesn’t match what was observed at all (see above). Below is a graphic from the 25th of December 1758 when Palitzsch was supposed to have observed the comet but by this stage according to the simulator the comet is moving away from the Earth and had already gone through perihelion! This is clearly wrong. I can’t see how they can display this incorrectly or am I doing something stupid? If you have time could you please check it for me? I’d greatly appreciate it.

Otherwise, I think the RA/Dec data from the orbit viewer is okay for the 1759 reappearance, at least the constellations match what Messier was describing.

As I said I created this thread for my benefit really as it forces me to look in more detail at the events surrounding these sightings so it gets cemented into my brain. It is all quite fascinating.

Hi stateless,

Yes - I’m perfectly aware (and have been since years) of the fact that the JPL orbit viewer is hopelessly useless when it comes to mapping the secular returns of periodic comets - such as Halley’s comet. This is also the case for the famed Stellarium simulator who also warns you that you need to install some special features in order to get correct ephemerides for comets.

However, comet C/1680V1 is a special case - since it has supposedly only appeared ONCE in the entire world history… See, it DOES nicely agree with - for instance - the perihelion of December 18 (as reported in the astronomy literature). So the question becomes: why would it NOT agree with the comet’s position only 11 days later (on December 29, 1680)? Are the JPL/NASA programmers simply inept?

Here’s the thing: the heliocentrists have had to build a nightmarish “computational edifice” around Newton’s and Halley’s cometary theories, replete with assorted perturbations / ‘gravitational’, ‘non-gravitational terms and whatnot. The very idea, for instance, that Halley’s comet can employ either 73 years or 79 years to return visiting our Solar System (as officially claimed) is patently absurd - and I dare say, laughable. No wonder then that their simulators are so recalcitrant to map our comets’ purported cigar-shaped, highly-elliptical orbits and variable speeds.

Hi Simon,
Point taken. What a world we live in.

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