[Alneyan]

I don't *think* you can create Suns in nebulas without removing the nebula first, if I recall correctly. It doesn't make a lot of sense, as the sun would effectively be hidden from view, so the game probably requires the nebula to be gone first.

In the stock game, red nebulas give cloaking level 5, so it's effectively invisibility until the nebula is removed (mines have the same cloaking level). The lowest level is 3, and that's the level of created nebulas as well.