The main star / Sun light source is a directional light which doesn't use range or attenuation, so its intensity is always the same. It could change if it was like a local light source and used a point light type, but it would decrease the performance, as calculating it is more expensive. Or the intensity of directional light could be decreased with distance, but all the lighting would change then and not only at the point of interest.

Changing light type can be tested or done in graphics clients first, as sun light is defined there, like in D3D7Client's Scene.cpp:

I think that, as far as seeing of planets far away is concerned, it wouldn't be a problem if more ships/UmmUs would be fitted with flashlights and if they could light planet surfaces.

Martin will have quite a lot of work for the next release...

@Tex; How about an alternative set of planet-textures that are simply darker?

That might look nice, but what about the ambient light reflected off vessels and other objects?

Stay in the cockpit, hotrod

Yeah, you're right, it's not a perfect solution.

Specular reflection off of the planet would probably also appear too strong and bright even if the texture is very dark (giving gray reflection off of the planet-mesh itself)

Just another thought on this; the adaptability of the human eye to different light-conditions. Wouldn't that fact make it quite arbitrary how bright a planet-surface would look to a human actually near it? The difference between being outside on a sunny day and then walking inside illustrates this clearly I would think; at first it appears very dark inside and then slowly as your eyes adapt to the lower brightness-conditions it changes. How would you simulate that effect realistically? A brightness level based only on the distance to the sun would not be enough, you would also need to factor in some sort of eye aperture effect as well as other eye-sight related effects (which might even differ from person to person just to make things even more complex)

http://en.wikipedia.org/wiki/Human_eye

Since most of the time we'd be sending unmanned probes, the problem goes back to the photon count. And definitely, there are fewer of those per unit aperture at the distance of Sedna - right now Sedna is as brightly lit as our own Moon.

It doesn't have to be all that complex. I'm just looking for a simple reduction of ambient light the further from the sun you are. Perhaps it could be adjustable, similar to the celestial sphere which allows you to adjust the brightness. That would allow users to tweak it to their preference/eyes.

I know this is an old issue but I was about to post something similar when I saw it. I think the effect described here could be accomplished by defining the sun as a local light source. The light level could then be reduced as a factor of distance.

As I understand it - the intensity of light is decreasing with distance like inverse square of the distance, like that:
It is really good suggestion Tex, I like it.

This is a wrong solution to illuminate surfaces of planets, like I've written in the first comment, but changing the intensity of already defined directional light with distance of camera relative to the star might be the solution (in the currently available, single star systems).

This is easy enough to implement, and I would be happy to do it, but I am not sure what function to use for intensity(distance). The physical 1/r^2 rule would not only be impractical, but also wrong, since it doesn't take into account physiological effects (dark adaptation etc.) Also, in practice if you go much closer to the sun or much further away, a spacecraft wouldn't provide a standard cockpit view anyway but instead use filters or image enhancers to provide something that the pilot can cope with. This would somehow have to be implemented as well (e.g. by adding graininess to symbolise a high-gain image amplifier).

I don't know about physiological effects but couldn't you implement a simple light reduction function for starters and then have a keyboard command to toggle filters on/off? That way you could view things realistically when you want to and still be able to see planets. The question is whether the filters should be implemented only in cockpit view or in external view as well.