<p>I've written a blog showing how you can do it with sample formula and python codings here:
<a href="http://bthoven.blogspot.com/2022/02/formulas-to-determine-or-create.html" rel="nofollow noreferrer">Formulas to determine, or create, the illuminated phase and orientation of the Moon (Moon tilt) at your location, as seen in your sky
</a></p>

CC BY-SA 4.0
2022-10-18T10:21:57.233Z
Link only answer is likely to be removed. Please add the relevant details in the answer so that user can see without having to go to the link.
Nilay Ghosh
CC BY-SA 4.0
2022-10-18T07:44:24.637Z
2022-10-18T07:44:24.637Z
bthoven
<p>I can compute the following data for the Moon for a given time and geographic location using the JPL Horizons system:</p>
<ul>
<li>Apparent RA &amp; DEC</li>
<li>Apparent azimuth &amp; elevation (AZ-EL)</li>
<li>Target range &amp; range rate (relative to observer)</li>
<li>Illuminated fraction</li>
<li>Phase angle and bisector</li>
</ul>
<p>Is it feasible to compute the shape and orientation of the crescent from this data and if yes
how is the computation procedure.
I would be grateful if any one can answer this question for me.</p>

CC BY-SA 4.0
2022-09-21T15:55:54.707Z
For the orientation, the largest factor is the "parallactic angle".  You can find many sources for info by searching for that term.
Greg Miller
CC BY-SA 4.0
2022-09-22T02:12:48.640Z
The best source for the computation of the physical appearance of the Moon is Astronomical Algorithms, by Jean Meeus [1998]. Do you have access to it (personal copy, library copy, etc.)?
Pierre Paquette
CC BY-SA 4.0
2022-09-22T02:40:59.133Z
There's also "24. Sun-Target-Observer angle", which includes stellar aberration on the down-leg from target to observer.
PM 2Ring
CC BY-SA 4.0
2022-09-29T09:12:54.973Z
Thank's for the answers. I can get a copy of Astronomical Algorithms, by Jean Meeus from the Bavarian State Library in Munich.
Klaus Rohe
<the-moon><positional-astronomy>
How can I compute the shape and orientation of the crescent for a given time and geographic location using data from the JPL Horizons?
Klaus Rohe
# How can I compute the shape and orientation of the crescent for a given time and geographic location using data from the JPL Horizons?

(Asked by: username_0 on 2022-09-21)

I can compute the following data for the Moon for a given time and geographic location using the JPL Horizons system:

* Apparent RA & DEC
* Apparent azimuth & elevation (AZ-EL)
* Target range & range rate (relative to observer)
* Illuminated fraction
* Phase angle and bisector

Is it feasible to compute the shape and orientation of the crescent from this data and if yes
how is the computation procedure.
I would be grateful if any one can answer this question for me.

**Tags:** the-moon, positional-astronomy

> **Comments:**
> **username_1**: For the orientation, the largest factor is the "parallactic angle".  You can find many sources for info by searching for that term.  
> **username_2**: The best source for the computation of the physical appearance of the Moon is Astronomical Algorithms, by Jean Meeus [1998]. Do you have access to it (personal copy, library copy, etc.)?  
> **username_3**: There's also "24. Sun-Target-Observer angle", which includes stellar aberration on the down-leg from target to observer.  
> **username_0**: Thank's for the answers. I can get a copy of Astronomical Algorithms, by Jean Meeus from the Bavarian State Library in Munich.  

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## 1 answers

### Answer by username_4 on 2022-10-18. Score: -1

I've written a blog showing how you can do it with sample formula and python codings here:
[Formulas to determine, or create, the illuminated phase and orientation of the Moon (Moon tilt) at your location, as seen in your sky](http://username_4.blogspot.com/2022/02/formulas-to-determine-or-create.html)

> **Comments:**
> **username_5**: Link only answer is likely to be removed. Please add the relevant details in the answer so that user can see without having to go to the link.  

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