Celestia Forums

(or, if you like 'Orbits not through their planets)

I have literally just now started using Celestia, and I think it's GREAT!

I found one strange thing though:
(I searched the forum, though admittedly not very hard, so forgive me if this has already been reported)

Especially with the outer Solar planets, when display of (planetary) orbits is on, the drawn path of the orbit doesn't pass through the centre of the planet. In most cases, it even falls outside of the orbits of most of the planet's satellites.

Aren't the drawn path of the orbit, and the drawn location of the planet, calculated from the same data?

(BTW, I noticed this while running the script 'Space Opera'.)

No, the orbits are by default drawn as 100 line segments between 100 chosen orbit points. The planet position is calculated every time step.

In the file celestia.cfg, you can adjust geometrical approximations like this, provided your computer would stand for the extra load. Look for these line and change the numbers after it (the first one adjusts line segments per orbit):



Spiff.

By default and to minimize overhead, Celestia calculates 100 points along an orbit just once and draws lines between them. If the orbiting body is not near one of those points, the closest line may not be near the body.

You can change the number of points by editing the text file celestia.cfg and changing the value specified for OrbitPathSamplePoints. Be sure to save a copy of this file before you edit it. It contains many other values that you can modify.

The way orbits are drawn will be changing in Celestia v1.4.0. It may improve this situation.

Thanks everyone! I expected it was something like that that I just hadn't discovered.

I changed it to 1000 and the curve now runs straight through the planet, and I didn't notice any effect in performance.