<p>Consider the vector positions of the center of mass of Moon, Sun and Earth, $\vec{r}_{\rm M}$, $\vec{r}_{\rm S}$, $\vec{r}_{\rm E}$, respectively, in a given reference frame. </p>

<p>Consider:</p>

<ul>
<li>the angle between the vector $\vec{r}_{\rm S} - \vec{r}_{\rm E}$ and $\vec{r}_{\rm M} - \vec{r}_{\rm E}$,</li>
<li>the angle between the vector $\vec{r}_{\rm E} - \vec{r}_{\rm S}$ and $\vec{r}_{\rm M} - \vec{r}_{\rm S}$,</li>
<li>the angle between the vector $\vec{r}_{\rm E} - \vec{r}_{\rm M}$ and $\vec{r}_{\rm S} - \vec{r}_{\rm M}$.   </li>
</ul>

<p>Does any of these angles have a name in astronomy, or can be important for some specific reasons? If so, may you please give me some general indications of why this is the case, and point to some references? </p>

CC BY-SA 3.0
2017-05-08T20:55:06.250Z
By the way, is there any good astronomy book focused on lunar theory that you would suggest?
James
<the-moon><natural-satellites><celestial-mechanics>
Angles in Moon, Earth and Sun system
James
# Angles in Moon, Earth and Sun system

(Asked by: username_0 on 2017-04-12)

Consider the vector positions of the center of mass of Moon, Sun and Earth, $\vec{r}\_{\rm M}$, $\vec{r}\_{\rm S}$, $\vec{r}\_{\rm E}$, respectively, in a given reference frame.

Consider:

* the angle between the vector $\vec{r}\_{\rm S} - \vec{r}\_{\rm E}$ and $\vec{r}\_{\rm M} - \vec{r}\_{\rm E}$,
* the angle between the vector $\vec{r}\_{\rm E} - \vec{r}\_{\rm S}$ and $\vec{r}\_{\rm M} - \vec{r}\_{\rm S}$,
* the angle between the vector $\vec{r}\_{\rm E} - \vec{r}\_{\rm M}$ and $\vec{r}\_{\rm S} - \vec{r}\_{\rm M}$.

Does any of these angles have a name in astronomy, or can be important for some specific reasons? If so, may you please give me some general indications of why this is the case, and point to some references?

**Tags:** the-moon, natural-satellites, celestial-mechanics

> **Comments:**
> **username_0**: By the way, is there any good astronomy book focused on lunar theory that you would suggest?  

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## 0 answers

