Talk:Halley's Comet

message: I may be dumb, but how about this statement about ellipticity: "(with 0 being a circle and 1 being a parabolic trajectory)" at the start of the Origin section.  It seems to me that the orbit with ellipticity 1 is a straight line to the barycenter.  Is that considered a parabolic trajectory?  I've always believed that ellipticity doesn't exist for parabolas, since the definition involves the semi-major and -minor axes. SkoreKeep (talk) 23:37, 10 August 2020 (UTC)
replies: text: Hold one vertex and one focus of an ellipse in the same place, and start increasing the ellipticity subject to that constraint.  As the ellipticity approaches 1, any fixed portion of the curve near the vertex will approach a parabola.  If you have further questions about this (which I think is sort of an interesting topic) the right place to ask would be the mathematics reference desk. --Trovatore (talk) 03:18, 11 August 2020 (UTC)
replies: text: That's eccentricity, not ellipticity. 89.168.85.237 (talk) 14:37, 1 July 2021 (UTC)
replies: text: Oops, my bad. --Trovatore (talk) 02:33, 19 November 2021 (UTC)
thread_title: Ellipticity

message: I see that the "minimum orbit intersection distance" (MOID) is given as about 0.06 AU, which seems to say that it can't hit the earth. But in AD 837 it may have passed as close as 0.03 AU, according to our article. Which means that the orbit gets perturbed enough to change the MOID from 0.03 to 0.06. So it seems obvious to me that it could equally well go back to 0.03 or to 0.00! And that means it could hit the earth. Rather unlikely, but it came pretty close in AD 837. Has anything been published about this possibility? Eric Kvaalen (talk) 15:26, 3 January 2022 (UTC)
replies: text: Thinking about it a bit more, it seems to be very unlikely. First of all, the MOID would have to be considerably less than 0.0001. And secondly, the timing would have to be just right as well. If it cut through the earth's orbit a few minutes before the earth gets to the crossing point, or a few minutes later, there would be no collision. The chance that the earth would be right at the crossing point within the time window of a few minutes is very small. So I suppose Halley will disappear or fly off into interstellar space before it hits the earth. But it would still be worth putting something into the article about this. Eric Kvaalen (talk) 15:43, 3 January 2022 (UTC)
thread_title: Could it hit the earth?

message: The article refers to the last year for which "oriental records were better than western" records. Shouldn't one compare oriental to occidental, or eastern to western records? This reads as grammatically confused. 216.163.246.3 (talk) 21:55, 17 October 2023 (UTC)
replies: text: Point taken. Serendipodous 23:57, 17 October 2023 (UTC)
thread_title:  Western vs Oriental 

message: If , so then you can surely edit this Wikipedia article for Halley's comet existing in 2024? 121.74.164.184 (talk) 04:43, 28 January 2024 (UTC)
thread_title:  Does halley's comet exist in 2024?  

message: In "Structure and composition" is "" which seems to do nothing. Anyone know what this is for or how to fix it? Al Begamut (talk) 22:47, 6 April 2024 (UTC)
thread_title:  ref label b?