Did the ancient Chinese, or at least pre-telescope Chinese predict comets?
The had fairly good records of them, but did anyone use those records to find repeating patterns and thus be able to predict the apparition of some comets? I’ve seen the claim that they did predict comets here and there. Is it true and which comets did they predict?
Bump!!!
I’ve never heard amny claims about this. Part of the problem is the very long time betwen comet’s returns, and another part is identifying the returning comet as the same one observed many years ago. It’s a nontrivial problem, and even when it was first done, predicting the return of Halley’s comet was cionsidered an impressive feat. The guy who did it – his name is unjustly not known by most people – was Johann Georg Palitzsch (Halley himself had died before the comet’s predicted return), and many people were skeptical of his claim, although it was soon vbindicated. Comet predicting is much tougher than you’d think. Why, in fact, ought one to think that comets even DID return? That was a pretty big leap of faith right there.
I’m curious about a much more mundane and likely propect – the observation and measurement of variable stars. As it turns out, Palitzsch was instrumental in this, too. He’s one of two people to measure the period of variation of the star Algol. He’s pretty much neglected for this, too – everyone remembers that John Goodrick did the same thing, at the same time (their articles re[porting the discovery are contiguous in the pages of the Journal of the Royal Society of London, and the values they obtained for the period almost identical) Goodricke was more 'photogenic", though – a teenage deaf-mute, who tragically died on pneumonia contracted from night air shortly thereafter. Palitzsch couldn’t get a break.
In any event, you’d think that the notion of variablre stars would be easy to come by, and the measurement of their periods straightforward – the stars are in the same place, and all you need to do is to observe and count. Yet the first mention of even the idea of a variable star didn’t occur until about the year 1600. Prior to that, there is no clear statement that variable stars even existed. No ancient text – Greek, Roman, Babylonian, Indian, or Chinese – explicitly refers to them. Such claims that they did write about them that I’ve investigated are ambiguous at best, untrue or over-enthusiastic at worst. I’ve argued at length that I thiink people knew about variable stars in the ancient world and even had measured periods (it’s enshrined and fossilized in mythology), but no one explicitly states it, for whatever reason
Asking whether the Chinese “predicted comets” is the same as asking whether they recognized the periodicity of Halley’s comet. It’s the only comet that’s bright enough, regular enough, and sufficiently short-period that one might recognize the periodicity without (a) telescopes and/or (b) knowledge of Kepler’s Laws by which to compute accurate orbits.
As it happened, Europeans didn’t recognize the periodicity until after those two advances. But they (or the Chinese) theoretically could have, or at least made a pretty good guess, by noting the large number of apparitions about 75 years apart.
I’ve never heard that the Chinese recognized Halley’s Comet as periodic, but I’m no expert on Chinese astronomy. I’d be interested in seeing a source for the claim that they did.
I guess Comet Encke fails on the regular part. Only 3 years, but not visible on each pass based on relative geometry. Plus it gets perturbed all the time. The linked article refers to a claim that Han-era astronomers might have noted it.
The world view of ancient observers might really have hindered things. Even Comet Halley would appear in different parts of the sky on each appearance, reducing the supposition that it was the same object. Only with a decent Sun-based geometry could someone figure out that it was more-or-less on the same path.
Thanks for the replies, everyone. I agree that it would be a real challenge for them to have predicted the apparitions of periodic comets. Especially since Halley’s comet can vary in it’s period by two to three years, due to perturbations by Jupiter or Saturn.
This question came up in another forum where I asked the trivia question of who first predicted the return of a comet. Everyone got the answer right, but one person said the Chinese had beaten him to the punch by a thousand years. Google found this Wikipedia page which has the line:
So I was wondering if this was right. If not, I wonder where the source of this misinformation is.
Nope. As you say you cannot “precisely predict” the appearance of a comet without understanding Newton’s Theory of Universal Gravitation and at least the approximate relative masses of the planets, so that you can calculate perturbations. For which, it helps if you’ve invented calculus.
Some random wikipedia editor had a vivid imagination. I’d edit it out, but their server is down.