The way it works is you pick a target (max range is 15000, enough to reach even Ogrovs without range boosters like the Akkan), and everything in a large radius around the target gets hit with a meteor for what was it, 500 damage? It works the same anywhere, doesn't matter if it's a star or asteroid belt or anything.
Rank 2 of the upgrade is currently bugged and the range is set to 0 
You can change it manually though by editing the appropriate file.
