Ara Pacis

2017-Mar-21, 06:17 PM

Does anyone have a list, or know where I can get a list of future apparitions of Comet Halley for about the next 1000 years? I've looked online and only see apparitions listed for 2061 and 2134. The best info I can find says that it varies between 74-79 years due to perturbations and numerical integrations can't be done more than a couple thousand years either direction, and those are variable by on the scale of a week for each apparition due to unpredictable outgassing. I looked at some planetarium programs, but Stellarium won't run and Home Planet doesn't get the last few or future few predictions anywhere close.

Or maybe it's not predictable at all, if I read the conclusion in this paper (https://arxiv.org/pdf/1409.7762.pdf) correctly.

Finally, we have computed the Lyapunov exponent for the present day Halley’s orbit and a series of other orbits differing in a and e by an amount equivalent to the observational uncertainty. We have found that L is greater than zero with a value of approximately 10−2, indicating that the orbit is indeed chaotic. The corresponding timescale for the prediction of Halley’s orbit to within present day observational constraints is less than 100 years, suggesting that the orbit of Halley’s comet can not be accurately predicted for timescales much greater than this

Although this paper (https://arxiv.org/pdf/1606.07037.pdf) suggests Lyapunov is closer to 300 years.

We find the Lyapunov time scale of Halley’s orbit to be of order 300 years, which is significantly longer than previous estimates in the literature. This discrepancy could be due to the different methods used to measure the Lyapunov time scale. A surprising result is that next to Jupiter, also encounters with Venus contribute to the exponential growth in the next 3000 years.

They claim Venus is the main perturber for the next few thousand years until Jupiter takes over. Still, the paper doesn't list any dates for future apparitions. A video here (https://www.youtube.com/watch?v=0G6vnq1TcRk) by one of the authors might be useable if it wasn't moving so fast or if I could DL it to do frame by frame analysis. Putting it at .25 speed and using the slider at full screen reveals they have an orbit taking ~150 years instead of ~76. So... :wall:

I found another post (https://forum.cosmoquest.org/archive/index.php/t-159729.html) linking to http://orbitsimulator.com/gravitySimulatorCloud/simulations/1452654910254_halley.html, but how accurate is this? The dates it renders for perihelion (guessing by looking at the map) are:

2061 Jun 28

2134 Mar 23

2209 Jan 26

2284 May 19

2358 Jun 04

2430 Jul 02

2504 Aug 16

2579 Aug 10

2653 Nov 27

2726 Jan 16

2795 Nov 11

2863 Nov 9

2931 Sep 17

3000 Aug 22

No wonder writers give up on hard SF and just go for science fantasy or space opera.

Or maybe it's not predictable at all, if I read the conclusion in this paper (https://arxiv.org/pdf/1409.7762.pdf) correctly.

Finally, we have computed the Lyapunov exponent for the present day Halley’s orbit and a series of other orbits differing in a and e by an amount equivalent to the observational uncertainty. We have found that L is greater than zero with a value of approximately 10−2, indicating that the orbit is indeed chaotic. The corresponding timescale for the prediction of Halley’s orbit to within present day observational constraints is less than 100 years, suggesting that the orbit of Halley’s comet can not be accurately predicted for timescales much greater than this

Although this paper (https://arxiv.org/pdf/1606.07037.pdf) suggests Lyapunov is closer to 300 years.

We find the Lyapunov time scale of Halley’s orbit to be of order 300 years, which is significantly longer than previous estimates in the literature. This discrepancy could be due to the different methods used to measure the Lyapunov time scale. A surprising result is that next to Jupiter, also encounters with Venus contribute to the exponential growth in the next 3000 years.

They claim Venus is the main perturber for the next few thousand years until Jupiter takes over. Still, the paper doesn't list any dates for future apparitions. A video here (https://www.youtube.com/watch?v=0G6vnq1TcRk) by one of the authors might be useable if it wasn't moving so fast or if I could DL it to do frame by frame analysis. Putting it at .25 speed and using the slider at full screen reveals they have an orbit taking ~150 years instead of ~76. So... :wall:

I found another post (https://forum.cosmoquest.org/archive/index.php/t-159729.html) linking to http://orbitsimulator.com/gravitySimulatorCloud/simulations/1452654910254_halley.html, but how accurate is this? The dates it renders for perihelion (guessing by looking at the map) are:

2061 Jun 28

2134 Mar 23

2209 Jan 26

2284 May 19

2358 Jun 04

2430 Jul 02

2504 Aug 16

2579 Aug 10

2653 Nov 27

2726 Jan 16

2795 Nov 11

2863 Nov 9

2931 Sep 17

3000 Aug 22

No wonder writers give up on hard SF and just go for science fantasy or space opera.