Talk:Solar coordinate systems

stonyhurst explanation

The explanation of stonyhurst system doesn't give any indication of which direction latitude an longitude go. I suppose positive latitude numbers mean up, but it doesn't say which way is up. For longitude which way is left, and is it positive or negative? Does up change from morning to evening, or northern/southern hemisphere on earth? ~2026-26254-77 (talk) 23:51, 29 April 2026 (UTC)

Helicentric coordinate frames

My understanding is that 'Solar ascending node on ecliptic' and 'First point of Aries' actually describe the same thing. Similarly, 'Sun–Earth line' and 'Intersection between solar equator and solar central meridian as seen from Earth' also define exactly the same axis. This is confusing and suggests way more complexity than there actually is. Apparently, there are just two options, keeping the +X axis fixed in space or permanently aligned towards Earth. I therefore suggest to pick one description for each of the two cases and use it consistently multiple times. For the +Z axis, there are also just two terms 'Ecliptic north pole' and 'Solar rotational axis'. It is very clear, that if one has for each axis two reasonable choices, one ends up with four combinations of these. --~2026-43031-61 (talk) 12:55, 4 August 2026 (UTC)

The solar equator is inclined with respect to both the celestial equator and ecliptic, so all of these directions are different. First,

• the "solar ascending node on ecliptic" is an intersection of the solar equatorial plane with the ecliptic, while
• the "first point of Aries" is an intersection of the celestial equatorial plane with the ecliptic.

And second,

• the "Sun–Earth line" points to the intersection between the ecliptic and solar central meridian as seen from Earth (hence "heliocentric Earth ecliptic"), which differs from
• the "intersection between [the] solar equator and solar central meridian as seen from Earth" (hence "heliocentric Earth equator").

CoronalMassAffection (talk) 00:08, 10 August 2026 (UTC)