Talk:Apsis

uncertainty

What are the uncertainties for aphelion and perihelion? Some values come from Kepler's laws, but not them, so they aren't so easy to measure. It looks like the article takes a value in A.U., and converts to km and mi with more digits. But how many should it have? — Preceding unsigned comment added by Gah4 (talk • contribs) 06:14, 29 September 2020 (UTC)

Terminology section

This section kind of repeats itself and duplicates it's information several times just structured differently. It clearly needs restructuring. Question is in which way the information could be most clearly presented? I would prefer to remove the point list, expand the normal text (under the etymology heading) slightly and keep the table of different terms. If no one objects, I will try to get back and do it. In the meantime suggestions are welcome and by all means feel free to edit it (who knows if I ever get around to do it). Amphioxi (talk) 12:53, 30 April 2021 (UTC)

table of aphelion and perihelion dates

due to the presence of leap years, it is difficult to guess the length of the years. Is it possible to add this datum? I suppose that should be easy for someone that manages well the software. thanks. pietro 151.29.59.56 (talk) 23:40, 27 May 2022 (UTC)

Exact time

Earth’s aphelion in 2025 occurs 2025.07.03 19:54:54 UTC (GMT +0) [ https://www.phpsciencelabs.com/nasa-jp-horizons-perigees-and-apogees-calculators/NASA-JPL-Horizons-Earth-Perihelion-Aphelion-Calculator.php ] not 20:02 Voproshatel (talk) 04:49, 30 June 2025 (UTC)

Looking at https://www.phpsciencelabs.com/phpsl-wiki/doku.php?id=programs-index it appears that this might be based on DE405 which is from 1998. Needs more looking into. I know DE440 moved the Sun's barycenter by ~100km, but I do not know if the updates would change the timing for center-center calculations. We are talking about a difference of 7 minutes and 6 km (or 4E-8 AU). -- Kheider (talk) 17:12, 30 June 2025 (UTC)

I see that Espenak1998 that used the 27-year-old DE405 lists the perihelion date for 1584 as Dec 28, whereas DE441 more accurately shows Dec 26. -- Kheider (talk) 14:29, 1 July 2025 (UTC)

I suggest to check the exact definition of perihelion: is the minimum distance of the Earth Center-of-Mass or of the Earth+Moon one? ~2026-36692-40 (talk) 18:10, 24 July 2026 (UTC)