First up, there is no 3.6.10 Zeta.
If you mean 3.6.8 Zeta, that's fine.
Between then and now, Stellar Enhancements package was put in. They were in the preceding 3.6.10's and in these 3.6.10's. Nothing in terms of that changed.
If there are differences in mission regarding the lighting between the LAST 3.6.10 and THIS 3.6.10, then we need to be aware of this, even though nothing has changed that should have caused any differences.
In the "Surrender, Belisarius" mission, there is still a sun. Look at the planet. Rotate the ship in the direction the planets highlighting is showing you that the sun should be in. You can't miss it. And nothing changed regarding the ambient light level in the mission. And since 3.6.8, all iterations of 3.6.10 have included Lightspeeds nebula. But again, the stellar enhacements package may have adjusted some of the background per mission that will have them looking different than in 3.6.8 Zeta or Retail.
Further, the 3.6.8 sun being green is _bad_. Retail does not have a green sun, it has a Gold sun.