Feature Request: Transparent Planet Color

[maxim]

For a planned educational addon I would need the possibility to set a planets base color to transparent - means a alpha channel setting additionally to the RGB colors. The according ssc entry should then look like this:

color [ 0.0 0.0 0.0 1.0 ]

If this can be involved without hard tweaking, it would be nice to have.

maxim

[eburacum45]

Certainly! I think a transparent planet could be used as a basis for a representation of a Dyson Swarm.

Solid Dyson spheres are quite unlikely, as they would be very dificult to support against the gravity of the star; but a swarm of independent elements could collect the light of a star while remaining in orbit.

Here is an image I made earlier, before I started using Celestia;
http://www.orionsarm.com/civ/Dyson_Spheres.html
http://planetary.org/news/2004/dyson_spheres.html

a transparent sphere or several concentric spheres covered in red orbital elements (to represent the radiated waste heat) could depict a Dyson swarm quite efficiently.

Or is this already possible in Celestia, and I missed it?

[selden]

Don't forget that you can create your own 3D models for use within Celestia. Spheres with surface texture images are particularly easy.

[maxim]

That may be suitable for custom planetary bodies, but would heavily interfere with existing ones.
In my case it would be used for the solsystem planets, and I'd like to avoid too much tweaking of the default implementation.

maxim

[Jeam Tag]

Don't forget that you can create your own 3D models for use within Celestia. Spheres with surface texture images are particularly easy.

Selden, please:
How can I really make a Dyson Sphere: i try a sphere like your for infrared sky, but i don't to make it opaque when we are outside the sphere.
Other questions: how to make clouds run inside the sphere? And to add model (like Gusev crater by Jestr) on the inside surface?
Jeam

[selden]

Jeam,

Sorry: you do have to learn how to use one of the 3D modelling programs. I suggest Anim8or. It's free and a lot easier to learn than most of the others.

My map sphere has its surface normals pointing toward the inside. As a result, you can only see the side that is farthest from you. In Celestia, you can only see surfaces that have their normals pointing toward you. To see the side that's closest to you, so you seem to see its outside, you need a model that has normals pointing toward you -- toward its outside.

So far as the physics is concerned, there would be no clouds or air on the inner side of a solid Dyson sphere. They'd all fall into the sun.

When you are inside it, there is no gravity to pull you toward the inside surface of a spherical shell. The gravity of the surface near you is exactly balanced by the gravity pulling you toward the opposite side of the shell on the far side of the sun.

For this same reason, gravity would not keep a shell centered around its sun. A real Dyson sphere probably would have to consist of many separate bodies orbiting their sun. Too much energy would be needed to keep a solid one in the right place.