Super Mario Galaxy 2/Sky Station Galaxy

Star 1: Peewee Piranha's Temper Tantrum
Upon arriving on the first planet, jump into the orange pipe to collect a 1-Up mushroom, then go down the green warp pipe to teleport to the other side. Once on the other side, climb up the small hill and break the large crystal. Fall down the hole after destroying the crystal and you will appear on the roof of Yoshi's house on the first side of the planet. The Luma on top of the roof will turn into a Launch Star, which lets you proceed to the second planet.
 * First planet

Follow the Luma, who will lead you up to the top of the planet. You can stomp or spin the Octoombas along the way, but avoid the rocks they spit at you. Time your use of the platforms so you jump off while they start blinking blue, which means they're about to disappear. You'll find another 1-Up mushroom on the platform right before the checkpoint. Right behind the checkpoint is a ? Coin that will create a path of music notes. Follow the path and collect all the notes for three more 1-Up mushrooms (it may help to clear out the enemy down the path first). After the notes, the Luma will continue up, but if you go to the back of the grassy area, you will find a blue warp pad that will take you to a time trial. If you do the time trial, collect the Rainbow Star and quickly run around the area hitting enemies. When you kill them all, three 1-Up mushrooms will appear on the stump in the center. When the time is up, whether you got all the enemies or not, you'll warp back up to the second planet. Continue up the sets of yellow rising platforms until you find the Luma, who will turn into a Launch Star.
 * Second planet

The next area is a small grassy planet with a smaller moon. You can backflip and spin at the bottom of the grassy one to be launched into another ? Coin, which turns into a bunch of collectible normal coins, or you can wait until the other Launch Star takes you through there. Eventually you'll need to jump to the moon where you can ride the small Launch Star there. This will take you on a circuitous orbit to a big Launch Star. If you don't spin immediately at the big one, you'll fly around to the previously mentioned Launch Star where you can get the ? Coin if you haven't already, and finally you'll come full circle back to the big Launch Star. If you still don't take it, you'll drop down onto the dirt planet below where you can collect four coins. When you do decide to take the Launch Star, you'll fly to the next planet.
 * Third planet


 * Fourth planet

This is a cylindrical planet with strips of dark mud that will slow you down dramatically and two rolling platforms that circle the planet. Hit the checkpoint flag and start moving along the planet. At the first rolling platform, you can run quickly on the lighter dirt parts to get across, but don't get stuck in the dark mud. You can ride this first platform (backflip when it gets to you) for a 1-Up mushroom. On the other side of the first platform there is another 1-Up mushroom in the breakable crystal there. Continue up the planet to the second platform, which will take you around to the Comet Medal. On the other side of the second platform follow the Luma to the top of the area where it will transform into a Launch Star for you.

You start off on the dark side of this planet, where you'll see a Life mushroom and a checkpoint flag. Grab the Life mushroom to get an additional three segments on your life gauge, then proceed past the checkpoint flag to the other side of the planet. On the back side of the platform with the Launch Star on top is another 1-Up mushroom, and from there you can backflip up to the top an avoid the enemies on the front side. Ride the Launch Star to the boss area.
 * Fifth planet

To damage the boss, simply use your spin attack on his rear end seven times. It takes three hits to break his egg shell, after which he will run away from. When you get the next hit on his unprotected rear, his shell will reappear and you'll need to get in another two hits to break it, then a final hit to end the fight. While he has his shell on, he will chase you around and occasionally jump into the air trying to slam down on top of you. You can use star bits at any time during the fight to slow him down. After defeating the boss, grab the shiny Power Star that he releases.
 * Peewee Piranha

Star 2: Storming the Sky Fleet
Avoid the Chomps that are rolling around in set paths or break them open by spinning the bouncing bushes into them, and go down the warp pipe to appear on the underside of the planet. If you follow the path around the planet counterclockwise, you can get a Rainbow Star in the first chest, which can also be opened by spinning a bouncing bush into it. The next chomp after the Rainbow Star has the key to unlock the Luma, and there is also a 1-Up mushroom in the chest by it. Go back to the Luma, who will turn into a Launch Star for you when you talk to it.
 * First planet

On the next planet, Banzai Bills will come toward you. Walk towards them and to the left to find a Rainbow Star, then continue in this diagonal direction to find a doorway inside the glass. Here you will be confined to a two-dimensional puzzle, and you'll see a 1-Up mushroom right above the checkpoint flag. You can go right past the checkpoint flag until you fall down (and around) to land on the platform above where you start. While falling, keep right to land on the platform above the electric orb, or backflip up to it from the lower one. Continue to the right, using the cogs to reach the Launch Star on the bottom right. Riding the last platforms on the right, you'll go past the Launch Star, another 1-Up mushroom (crouch and walk to get to it), and a time-trial warp. When you're ready, jump into the Launch Star while avoiding the electric orbs to go to the next planet.
 * Second planet

Here you'll see a checkpoint flag between two logs and a pattern of eight blue ? panels in front of you. Tag the checkpoint flag and touch each one of the Question Blocks to turn them yellow. Touching a yellow panel will turn it back to blue, so try not to backtrack. Go in the following order, pausing at 6 to let the Banzai Bill pass, and grabbing the 1-Up next to 7 if you want. 6 7 5 4 8 2 3 1 When you've lit up all the panels yellow, they'll turn green permanently and the next area will open up.
 * Third planet

Avoid the Cosmic Clones on the next set of color-changing tiles to reveal the Launch Star. If you run into one of your clones you'll lose a segment of your life bar, so use the following path and try not to backtrack. 11 12 13 14 10 -- -- 15 9 6  5  4 8  7  2  3       1

The next checkpoint flag precedes a gauntlet of Banzai Bills. Avoid the mud in front of the second cannon and follow the third Banzai Bill out to a platform with a Prickly Piranha Plant. Use the bouncing bush to defeat the larger Piranha Plant and retrieve a key to unlock the Power Star. Carefully retrace your steps back to the Power Star by waiting in the lower part for the Banzai Bill to pass overhead, then hurrying back the way it came.
 * Fourth planet

Star 3: Peewee Piranha's Speed Run (Prankster Comet)
This mission requires you to complete part of Peewee Piranha's Temper Tantrum again but with only 20 seconds to complete the level. The green timers add 10 bonus seconds to your clock, so looking for these is your first priority. Even missing just one green timer could result in failure.

When you start out, go left to the green pipe, then up the hill through another bonus timer to break the glass. Launch to the next planet and cross the mud in front of you and pick up another bonus timer, then long jump across the dirt area and head up the planet. Get on top of the second rolling platform for the bonus timer right there, and stay on while moving to the other side of it. It will take you through another bonus timer and you can hop off right at the Launch Star that will take you to the boss. Do this fight the same as you did before and don't worry about the time because there are plenty of bonus timers lying around the planet.

Green Stars
On the first planet, go around to the other side of Yoshi's house and backflip in the Green Star's shadow by the wall of the building to get the first star. The second Green Star is on the second planet. Go up to where the Launch Star is, but do not use it. Instead, rotate the camera around so you can see the Green Star below the white fence next to you, and hop over the fence to get it.
 * Green Star 1 or 2

On the second planet, inside the glass cylinder, ride the farthest right platforms up to where the blue warp pad for the time trial is. The Green Star is located above it. You can get to it by long jumping off the platform, or by backflipping and wall jumping from below it.
 * Green Star 3