Talk:Perihelion and aphelion

Un-redirect
I don't know whether this un-redirect is required or not. But one thing that I can say: either apsis and periapsis need there own pages, or apsis needs to be seriously rewritten. Because it's extremely confusing in its current form. &mdash; Gopher65talk 22:44, 8 August 2014 (UTC)
 * Well that was my reason for providing this article. Someone had found it necessary to provide a link within the Apsis article to Perihelion! Obviously this article needs a referral to Apsis and clearly the maths only needs to be in one place. But the Apsis article is still trying to do too much—in particular, many people are only interested in solar orbits and the -helion and -gee terms are far more widely used. Chris55 (talk) 10:26, 10 August 2014 (UTC)


 * I would advocate that this article be moved to the title Perihelion and aphelion with redirects from both Perihelion and Aphelion. The only thing from the current aphelion article that needs to be moved into this one is the Greek etymology.
 * I'd be happy with that.
 * I would also advocate moving to this article the entire apsis sections Apsis and Apsis, but if you try to do that you may tread on some toes at the aphelion article. 208.50.124.65 (talk) 20:09, 3 September 2014 (UTC)
 * I think you mean the Apsis article. But your caution may be justified. Let's do one at a time. Chris55 (talk) 12:39, 4 September 2014 (UTC)

Glaring contradiction
According to the text: "The perihelion is the point in the orbit of a planet, asteroid, comet or other star-orbiting body where it is nearest to its star." But then look at the image:



If you draw a vertical line through the star, the two points of intersection with the orbit are both closer than the point marked as perihelion. Obviously, either the definition or the image is wrong. (Presumably the image: the star is not at the focus of the ellipse.) 2602:306:CEAE:E60:940E:7689:8DC5:2704 (talk) 17:30, 24 September 2015 (UTC)


 * It's not a contradiction, just a very poor diagram. The "ellipse" is more like an oval and badly exaggerated. In fact the difference between perihelion and aphelion is less than 10% for most of the planets which doesn't help to make the point either. A better diagram is badly needed! Chris55 (talk) 20:32, 26 September 2015 (UTC)


 * Ok, I've put a somewhat better picture there. It's still exaggerated but at least the focus is in approximately the correct position and you can see that your objection no longer holds. Chris55 (talk) 22:21, 26 September 2015 (UTC)


 * In fact it's perfectly clear even without the exaggeration. So I've now scaled it to approximate to the earth's orbit. (The sizes of the bodies are not to scale.) Does anyone think it needs the exaggeration? Chris55 (talk) 09:53, 27 September 2015 (UTC)

Remove redundancies
Para 4 (explanation of seasons) has IMHO nothing to do with perihelion and aphelion. I suggest replacing it with a short note that Earth's distance from the Sun does not significantly affect what season occurs. --212.114.247.97 (talk) 10:15, 22 January 2016 (UTC)
 * This seems to have been expanded since you wrote. (I added the section heading.)  It does now explain exactly what causes the seasons.  You are correct that it has nothing to do with perihelion and aphelion; and in the Northern Hemisphere, is even counterintuitive.  Spike-from-NH (talk) 02:37, 7 November 2016 (UTC)
 * PS--I've now rewritten it further, following your suggestion, to reduce the text that is unrelated to perihelion. Spike-from-NH (talk) 22:52, 7 November 2016 (UTC)

Earth
So when do the Earth's perihelion and aphelion occur? The article currently just says 'early January' and 'early July'. Do they happen on the same dates each year, as the solstices and equinoxes do, or do they vary a bit? Why? — Preceding unsigned comment added by 203.2.218.131 (talk) 02:00, 7 November 2016 (UTC)


 * More precise dates are given at I've copied in the dates and another sentence from Earth. Spike-from-NH (talk) 02:32, 22:53, 7 November 2016 (UTC)

"What this is not"
Anon and have added too much detail in the article's first paragraph along the lines of "what this is not." Information on incorrect use of the term might fit in a Notes footnote or further down in the article. Spike-from-NH (talk) 04:34, 10 November 2017 (UTC)

Perihelion and hyperbolic trajectories
This article could clarify that perihelion/perigee/periastron/pericenter exists for hyperbolic trajectories. Tom Ruen (talk) 09:10, 19 December 2017 (UTC)

Say what the temperature differences would be if the perihelion occurred in the northern summer
Perhaps mention World temperature differences if the perihelion occured during the northern summer. Jidanni (talk) 09:39, 8 December 2018 (UTC)