The Great Darkness

[Formendacil]

With regards to Sauron, I have to go with the consensus, and chime in with saying that Sauron's "Second Darkness" would have been a figurative term.

With Morgoth, however, obliterating light and therefore totally destroying everything was more or less his goal. Looking at the essays on Melkor in HoME, Volume X, Morgoth's Ring, you'll see that Morgoth was set on a path that unthwarted would have led to total annihilation of first all good things, then his own servants, and then the world itself, in so far as he was able.

In the same context though, it says that Sauron was not quite so depraved. Sauron did not object to the mere existence of the world (as Melkor did), so long as he could do what he wanted with it.

I would apply the same logic to the sun and moon, had Sauron succeeded in taking over middle-earth. He would not have objected to their live-giving properties, so long as all the life they gave came under his dominion.