Elemental Stars

From Golden Sun - Wiki on Neoseeker

The four Elemental Stars are the items that need to be thrown into each Lighthouse's beacon to light the Lighthouse. Each Star must be thrown into the Lighthouse of it's own element. The Element Stars are found in the first game at Sol Sanctum, and the Jupiter, Venus, and Mercury Stars are taken. The Mars Star is the only Star that Isaac and co are able to hang on to, but they lose that star as well at the end of the first game.