Wonders - planet of origin or entire empire?

[EternalSpark]

Here's the deal:

I've just finished a war with the Torians, with them surrendering to the Alien Race That Trades A Lot Whose Name I can't remember.

I don't mind, as a decent amount of surrendered bases were already going into cultural chaos.

Then they built the Wonder That Prevents Defections.

Now, does that wonder only cause the planet it's built on to be Defection-Proof, or all of 'em?

[Gufnork]

Just the planet it's built on. It's not actually a wonder, but a special project, which means that every civilization can built it but only once. So you can make one planet immune to defections throughout the game (of course, you could invade a planet with one to get an extra).