Can I change the color of ambient light?

[Algiark]

If so, how?

 

[Snark]

Moving to Gameplay Questions.

I don't think there's any way to do this in the stock game.

If you're interested in nicer lighting effects, I strongly recommend the mod PlanetShine.  It's simple, lightweight (doesn't strain your GPU), and gorgeous.  Totally should be stock, IMHO.  Tinkers with ambient lighting, and adds "reflected" glow from planets so that, for example, if you're orbiting over Duna's sunlit side, the underside of your ship has a red glow.  Really looks nice.  (It also gives a nice "glaring whiteout with stark black shadows" effect when you get really close to the sun.)

[Alshain]

Alternatively if all you want is to lower or raise the ambient light, there is the Ambient Light Adjustment mod.  This one is especially useful for YouTube and Twitch producers.

Link to PlanetShine that @Snarkmentioned.

For more specific lighting needs, there is Engine Lighting and but Bulb which are not ambient light, but may help you get the effects you really want.