<p>As someone commented, you are actually short a term for fully defining the orbit.  The "azimuth" as you describe is commonly defined as a "longitude of perihelion", and you're forgetting the orientation of the inclination, commonly defined as "longitude of the ascending node." (Both of these values are included in the first link in the previous posted answer) </p>

<p>For a more detailed look at the math which uses the defining values, JPL made a whitepaper which goes into the math, and also allows you to account for changes in the orbital terms.  (Most of the math you're probably looking for is at the end of the document, beginning about section 8.10, on page 25)</p>

<p><a href="ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf" rel="nofollow">ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf</a></p>

CC BY-SA 3.0
2016-02-19T06:03:16.343Z
2016-02-19T06:03:16.343Z
nflemming2004
<p>The Keplerian elements for the planets provides all of the information needed to define the orbit and where the planet is currently along it.</p>

<p>Approximate elements are available from JPL and can be found here: <a href="http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt" rel="nofollow">http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt</a></p>

<p>If you don't want to do the math, you can just ask JPL Horizons to do it for you and calculate an ephemeris telling you which direction each planet is in right now: 
<a href="http://ssd.jpl.nasa.gov/horizons.cgi" rel="nofollow">http://ssd.jpl.nasa.gov/horizons.cgi</a></p>

CC BY-SA 3.0
2015-01-24T21:24:04.477Z
2015-01-24T21:24:04.477Z
John
<p>I am creating a virtual solar system model and I want it to be as realistic as possible (e.g. orbits are ellipses, not circles, and orbits are oriented correctly, not all coplanar).  In order for me to do this, I need to know the eccentricity of the orbit, the perihelion, the semi-major-axis, inclination and azimuth.  I have all of this information, except for the azimuth of the orbit, which is the angle from the sun to the aphelion.  Are there any reliable sources with this information?</p>

CC BY-SA 3.0
2014-11-18T02:53:21.660Z
http://en.wikipedia.org/wiki/Orbital_elements
rnrneverdies
CC BY-SA 3.0
2014-11-18T08:52:19.383Z
Can you please give a better definition of azimuthal angle in this case? Even better, would be if you would use the right terminology, according to the page linked by the OP above.
Py-ser
CC BY-SA 3.0
2014-11-18T09:31:04.930Z
As noted in the wikipedia article, one needs seven parameters to specify an orbit, the epoch time plus a set of six values that represent the orbit at that point in time. The canonical set is $a$, $e$, $i$, $\Omega$, $\omega$, $M_0$, and $t_0$ (semi-major axis, eccentricity, inclination, right ascension of ascending node, argument of perigee, mean anomaly, and epoch time). Vinnie Caprarola, you only list five parameters in your question.
David Hammen
<orbit>
What are the azimuths of the planets' orbits?
vcapra1
# What are the azimuths of the planets' orbits?

(Asked by: username_0 on 2014-11-17)

I am creating a virtual solar system model and I want it to be as realistic as possible (e.g. orbits are ellipses, not circles, and orbits are oriented correctly, not all coplanar). In order for me to do this, I need to know the eccentricity of the orbit, the perihelion, the semi-major-axis, inclination and azimuth. I have all of this information, except for the azimuth of the orbit, which is the angle from the sun to the aphelion. Are there any reliable sources with this information?

**Tags:** orbit

> **Comments:**
> **username_1**: http://en.wikipedia.org/wiki/Orbital_elements  
> **username_2**: Can you please give a better definition of azimuthal angle in this case? Even better, would be if you would use the right terminology, according to the page linked by the OP above.  
> **username_3**: As noted in the wikipedia article, one needs seven parameters to specify an orbit, the epoch time plus a set of six values that represent the orbit at that point in time. The canonical set is $a$, $e$, $i$, $\Omega$, $\omega$, $M_0$, and $t_0$ (semi-major axis, eccentricity, inclination, right ascension of ascending node, argument of perigee, mean anomaly, and epoch time). Vinnie Caprarola, you only list five parameters in your question.  

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## 2 answers

### Answer by username_4 on 2016-02-19. Score: 1

As someone commented, you are actually short a term for fully defining the orbit. The "azimuth" as you describe is commonly defined as a "longitude of perihelion", and you're forgetting the orientation of the inclination, commonly defined as "longitude of the ascending node." (Both of these values are included in the first link in the previous posted answer)

For a more detailed look at the math which uses the defining values, JPL made a whitepaper which goes into the math, and also allows you to account for changes in the orbital terms. (Most of the math you're probably looking for is at the end of the document, beginning about section 8.10, on page 25)

<ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf>


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### Answer by username_5 on 2015-01-24. Score: 0

The Keplerian elements for the planets provides all of the information needed to define the orbit and where the planet is currently along it.

Approximate elements are available from JPL and can be found here: <http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt>

If you don't want to do the math, you can just ask JPL Horizons to do it for you and calculate an ephemeris telling you which direction each planet is in right now:
<http://ssd.jpl.nasa.gov/horizons.cgi>


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