I'v just downloaded Celestia 130 , and I dont like the way it cast shadows . I'l explain: as you all know CTRL+V change specific OpenGL extension to display object. Well, when I set it to NVIDIA COMBINERS, some shadows are normal, and some look at any direction independent from light source . When set to NV COMBINERS AND VERTEX, the shadows ocour inverted (ex: mountain look like valey and etc.). It is extremely visible on planets with lot of craters (Mercury or moon) and mountains (Mars). I tried to play with bump map but its no use.
My PC:
Celeron 2 GHZ, 256 DDR RAM, GeForce4 MX (64 MB), Mother - Shuttle (VIA chipset or smth.), WinXP Pro.