<p>I suggest you use the JPL Horizons system. You can investigate how Charon's orbital elements change with time. The short answer is, not surprisingly, not by much. The values for the eccentricity I see hover around 0.00015 and those for the orbital inclination relative to Pluto's equatorial plane are about 0.09 degrees. </p>

<p><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
2016-04-09T20:27:23.897Z
2016-04-09T20:27:23.897Z
Dave
<p>For years I've been fascinated with the mutually tide-locked bodies Pluto and Charon. In July 2012, The Astronomical Journal published an article <a href="http://iopscience.iop.org/1538-3881/144/1/15/pdf/1538-3881_144_1_15.pdf">The Orbit of Charon Is Circular</a> by Buie, Tholen and Grundy. The authors thought that the eccentricity of Charon's orbit is very close to zero.</p>

<p>It seems to me their opinion is somewhat speculative given the low quality of images from Hubble. Has New Horizons data verified Charon's circular orbit? Is there an online source giving more precise orbital elements from New Horizons data?</p>

<p>I'm also interested in the obliquity of Pluto and Charon.</p>

<pluto><charon>
Has New Horizon's data updated Charon's orbital elements?
HopDavid
# Has New Horizon's data updated Charon's orbital elements?

(Asked by: username_0 on 2015-08-06)

For years I've been fascinated with the mutually tide-locked bodies Pluto and Charon. In July 2012, The Astronomical Journal published an article [The Orbit of Charon Is Circular](http://iopscience.iop.org/1538-3881/144/1/15/pdf/1538-3881_144_1_15.pdf) by Buie, Tholen and Grundy. The authors thought that the eccentricity of Charon's orbit is very close to zero.

It seems to me their opinion is somewhat speculative given the low quality of images from Hubble. Has New Horizons data verified Charon's circular orbit? Is there an online source giving more precise orbital elements from New Horizons data?

I'm also interested in the obliquity of Pluto and Charon.

**Tags:** pluto, charon

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## 1 answers

### Answer by username_1 on 2016-04-09. Score: 2

I suggest you use the JPL Horizons system. You can investigate how Charon's orbital elements change with time. The short answer is, not surprisingly, not by much. The values for the eccentricity I see hover around 0.00015 and those for the orbital inclination relative to Pluto's equatorial plane are about 0.09 degrees.

<http://ssd.jpl.nasa.gov/horizons.cgi>


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