Celestia Forums

Hey guys,
Just came across this and I thought you might find it interesting:
http://www.cnn.com/2002/TECH/space/10/2 ... index.html

This isn't my first post here, (but I just registered) and I know I've mentioned it before, but I just wanted to thank Chris again for this wonderful program! It rocks!

With that said, I was wondering if I could make a request?
I would love to see all of the moons of Jupiter, Saturn, Uranus, and Neptune in Celestia... Since I now have over 2 million stars, countless asteroids and comets, plus all sorts of neat spacecraft, thanks to all of the great add-ons I've found (My thanks to all the creators - you know who you are!), I was wondering when I might be able to see the 33 other moons of Jupiter?

OK, that was me - I thought I was logged in???

Oh well...

Well, have you considered providing the orbital elements yourself?

You can get them from JPL's Horizons ephemeris service and reformat them into Celestia's .SSC format. It just takes a little patience.

This should work, though I haven't tried it yet (cpu is busy with other things so I can't run celestia to test it):

"2001 U1" "Sol/Uranus"
{
Mesh "asteroid.cms"
Texture "asteroid.jpg"
Radius 10

EllipticalOrbit
{
Epoch 2451200.5
Period 758.1
SemiMajorAxis 8571000
Eccentricity 0.208
Inclination 166.33
MeanAnomaly 22.366
}
}

Well, have you considered providing the orbital elements yourself?

Actually, no, since I don't have the slightest idea how to...
I would be interested in learning, tho!

I hope my post didn't sound too rude, I was just playing. I have no complaints! I love this program and am thankful that it's free!

I have to admit, when I posted this I didn't have the minor moons update loaded, even though I thought I did. That's why I only saw a handful of moons... Sorry!

Cheers!
Sean

Sean,

To add an orbiting object, you have to create a text file with the filetyoe of .SSC in the extras directory. The actal name doesn't matter so long as it's unique.

The "minor moons" addon provides an example. You don't have to create that many objects at a time, of course. Ortolan shows the minimal information for a single moon up above here. Thomas Guilpain has provided a description of most of the declarations you can use in a .ssc file on his Web site.

Making the entries is usually just a matter of cutting and pasting the rignt numbers. You can get the orbital parameters from any of a number of Web sites. Google does a good job of finding them. JPL's Horizons epmemeris server is a good centralized source, but they won't have the most recent discoveries.

You'll need to do a little studying to understand what the various orbital parameters mean and why they're necessary. There are some books on astrodynamics available as well as Web pages that can help you get started.

Rather than include all the links in this posting, I'll just suggest that you click on the WWW icon belos my sig here.

I hope this helps a little.