<p>Given, the mean longitude L of the Earth-Moon barycenter, as seen from the Sun's center.
From this, is the mean longitude of the Sun L+180°, or is it 360°-L, as seen from the Earth-Moon barycenter?</p>
<p>Tried ChatGPT but this does not answer my question.</p>

CC BY-SA 4.0
2023-11-03T20:14:33.467Z
It is 180+L.  E.g. if EMB is at 0, then the Sun is at 180.  If the EMB is at 90, the Sun is at 270.
Greg Miller
CC BY-SA 4.0
2023-11-04T11:47:17.597Z
Indeed, this must be the right solution.
Petoetje59
<positional-astronomy>
Longitude from different vantage points
Petoetje59
# Longitude from different vantage points

(Asked by: username_0 on 2023-11-03)

Given, the mean longitude L of the Earth-Moon barycenter, as seen from the Sun's center.
From this, is the mean longitude of the Sun L+180°, or is it 360°-L, as seen from the Earth-Moon barycenter?

Tried ChatGPT but this does not answer my question.

**Tags:** positional-astronomy
> **Comments:**
> **username_1**: It is 180+L.  E.g. if EMB is at 0, then the Sun is at 180.  If the EMB is at 90, the Sun is at 270.  
> **username_0**: Indeed, this must be the right solution.  

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