The stars are always there. You can see them if you zoom out enough and you have "centered" the map. You should be seeing the Earth globe in front of them, which for some reason is not being displayed. I started a new game and I cheated a little with WorldBuilder so I could build Stonehenge (see in the attached picture how it is supposed to look).
You mention you are using Wine. I was able find some discussions online about Linux players experiencing the same problem as you. As a Linux user, you will probably understand them a lot better than me. ;)
* This post at Stack Exchange suggests some components to add to Wine that help an user fix the issue:
https://unix.stackexchange.com/questions/476801/civilization-iv-turns-into-a-black-screen-after-revealing-map * This discussion in the Steam forums explain how a user fixed it with "winetricks":
https://steamcommunity.com/app/221410/discussions/0/1750106661711803494/
* One of the comments at WineHQ wiki suggests running on window mode instead of full-screen and change the resolution settings:
https://appdb.winehq.org/objectManager.php?sClass=version&iId=10158&sAllBugs * And your go-to site for all things Civilization, CivFanatics, has this thread where a user fixed the problem as well (check post #124 by Pangaea):
https://forums.civfanatics.com/threads/wine-civ4-in-wine-1-1-25-on-ubuntu-9-04.327508/page-7 I hope one of these helps you fix the issue!
ConsulCaesar: Stonehenge "centers" the map, readjusting it so you see its real dimensions and your position on it.
benutzername.gog: Showing me how small I am in the universe I guess? ;-)
It's related to how Stonehenge is thought to be an astronomical monument, tracking the movement of the celestial bodies. The same effect happens when you research Calendar, a bit later in the game.