Super Mario Galaxy/Bowser Jr.'s Airship Armada

Bowser Jr.'s Airship Armada is accessible from the Kitchen observation dome. You need 23 Stars to enter.

This galaxy contains several airships floating in space.

Star 1 (Grand): Sinking the Airships
On the first airship, defeat several coloured Goombas, then fall down a hole at the front of the ship to land in a cannon. Fire yourself at the pole on the airship in front of you, which two mines appear to be circling (actually the mines are much closer to you.) Once on the second airship, run past the lasers and defeat or avoid the wizard, to go into another cannon.

Again aim at the pole. On the third airship, there is a Luma shop selling a 1-Up or a Life Mushroom for 30 Star Bits. If you do not yet have enough Star Bits, handily there are 31 to be gained on this ship, from the Wrigglers, Mandibug, ? block, and spinning while standing on a valve. Choose the Life Mushroom if you are unsure of your skills at defeating the boss who you will be facing soon.

Go down the walkway, defeat the Mandibug and go onto a platform. This platform will start moving once you spin the lever. You will need to avoid or fire Star Bits at the projectiles being fired at you. Fire Star Bits at spiders to get them out of your way (you won't be able to jump on them).

At other end, make your way to the fourth and final airship. Use the Sling Star to reach the deck.

Boss fight - Bowser Jr. Fire green shells at his ship. Avoid the projectiles he fires and the Bullet Bills. Kill the wizards that appear. Once you have hit Bowser Jr. three times he'll start firing fireballs at you too. Hit his ship two more times to defeat him.

There are various coins around to replenish health, including some embedded in the surface of the airship (fire Star Bits at them to release), in a glass cage, in the projectiles that Bowser Jr. fires at you (again, fire Star Bits to release these), and gained by killing the wizards.

When Bowser Jr. is defeated, collect the Grand Star, which as well as increasing your Star total will unlock the Bedroom dome.