You can also capture them with Dominate
Just set the Dominate to cover like: Frigates, CapitalShips, PlanetModules (Guns, Extractors, TradePorts, Labs, etc...) and if you really want to have things go really crazy add Planets to the list, haha. I did, and was kicking the Vasari, when the Tec sneaked in and dominated my planet and i lost
Haha, i fell over, i thought... well thats what i get for being fair. 
But it was cool anyway. 
-Teal