World 5 (Super Mario Galaxy 2)

"This place... It looks like it might be pretty well protected. I betcha we're moving right in on the enemy's home base. Whaddya say we drop in unannounced?"

- Lubba

World 5: Trial of the Galaxies is the fifth world featured in Super Mario Galaxy 2. World 5 is a galaxy cluster. It holds seven galaxies, the last of which, Bowser Jr.'s Boom Bunker, features the third and last encounter with Bowser Jr., who now attacks with his Boomsday Machine.

Trivia

 * This is the only world in the game where Yoshi doesn't appear in any galaxy.
 * This is the only world in the game where there are no Purple Coin missions.