I don't want to just stick this on the page, but it strikes me that the device, for its importance, is sorely underwritten. It's terribly easy to overlook it -- and therefore to have no way to win the game.
I agree it can be easy to overlook, but I think that's appropriate to a game where puzzles play a major part in gameplay. Its location is, after all, mentioned by at least two races besides the Mycon themselves, and talking to the Chmmr makes the Sun Device's use easy to figure out once it is acquired.
I would, however, add that there are at least two ways to acquire the Sun Device, and I have edited the article a bit to include the second one. When I first played, I could not figure out how to find the Syreen homeworld, and so could not ally with them -- but I still got the Sun Device, by waiting for the Ur Quan to destroy the Mycon once the Doctrinal War ends near the end of the game. I then had -just- enough time to use the Sun Device, get the Chmmr to upgrade the Antimatter Bomb and give me the Avatar Ships, and locate and destroy the Sa-Matra before the Ur Quan reached Earth. The sequence at the end of the game made it obvious that I missed something, of course, since it featured the Syreen, and also most of the races were wiped out by the time I won... but still, it's possible.
P.S. I meant the original Syreen homeworld, the one where the shell of the Mycon Deep Child is. Now THAT, I think, is 'under-written.'