Super Mario Galaxy 2/Spin-Dig Galaxy

Digga-Leg's Planet
This galaxy introduces the Spin Drill, which lets you burrow straight down in dirt until you come out the other side or you hit something you can't drill, in which case you'll turn around and come back out the way you entered. On the first planet, get the Spin Drill power-up while avoiding the Diggas, who can be killed by jumping on their backs or drilling into them from below. the places you want to drill are marked by shallow circles in the ground. The one in the center of the three towers will take you through the planet to the 1-Up mushroom inside the cage. You want to get up on top of the tallest tower, so drill from the opposite side of the planet. Talk to the Luma there and it will turn into a Launch Star to send you to the next planet.
 * First planet


 * Second planet

First, jump onto the non-dirt platform nearby with the red metal band around it. This will zoom out the camera for you so you can see the whole planet. The goal is to get up to the top of the tallest tower on the side of the planet you start on. You can see that you'll need to drill on the small dirt platform that doesn't have the Spin Drill on it, then walk over to the other side of the platform you end up on and drill again to go to the top of the big tower. You'll also see the Comet Medal off to the side of the smaller tower on the starting side of the planet. There is a similar non-drillable platform on the other side of the planet where the camera will zoom out for you. When you get to the top of the tallest tower, talk to the Luma to turn it into another Launch Star.

This area is a circular platform with Twirlips patrolling around it and disappearing blocks fading in and out to cross to other platforms. From where you start, there is a blue warp pad to a time trial going counterclockwise, and a 1-Up mushroom going clockwise. The time trial is an easy one, with eight Twirlips and a Rainbow Star. Just past the 1-Up mushroom going clockwise is a platform with a circle of coins and the path to it consisting of disappearing blocks and a Paragoomba guard. You can get over to the coins fairly easily by long jumping from the first set of disappearing blocks, so you don't have to worry about the rest of them. When you get over to the coins a Luma will show up and turn into a Launch Star for you.
 * Third planet

This small planet has three Goombas, a Spin Drill and a Launch Star on top of a short tower. You can just backflip and spin to get up the Launch Star, or you can grab the Spin Drill and drill into the planet. Inside of the planet are a bunch of coins, and you can spin in the hole at the top to go to the Launch Star. This takes you to the Toad Ship where you can talk to the Toad Brigade Captain or buy an item. The Launch Star over the checkpoint flag takes you to the boss, so if you have trouble with him you might want to purchase a Life mushroom to give you a few extra health segments. When you're ready, take the Launch Star to face Digga-Leg.
 * Fourth planet

To damage Digga-Leg, drill into him when his glass cage is facing down. Do this three times to obtain the Power Star. First off, run to the side to grab a Spin Drill, then jump on the Digga's back he sends down to you. Make sure you're directly across the planet from him before you drill to the glass cage. When he moves around, just stay on the opposite side of the planet and when he sends a Digga, don't worry too much about killing it as most often Digga-Leg will stomp on them himself. You can tell when Digga-Leg is about to turn over and show the glass cage because he'll start steaming, so you can get him right off the bat if you spin as soon as you see him do it.
 * Digga-Leg

Silver Stars Down Deep
On this planet, Cosmic Clones will chase you when you jump off the starting tower. The first thing you should do is break the crystal with the small Launch Star in it and use it to go up to the top of a tower with a Piranha Plant on it. After that you can go back down and explore without worrying about the clones. All the Piranha Plants on the planet turn into vines you can move along by shaking the remote, and there is also a normal plant that pops up with a vine as well. The best you can find are some star bits doing this, so if you want to leave the planet, just take out the Piranha Plant the Launch Star takes you to and the vine it turns into will let you get to the next planet.
 * First planet

This is a cylindrical space station that you can enter through the green warp pipe at the top. Next to the warp pipe is a teleporter to a time trial with eight Twirlips. Because there's no Rainbow Star it's somewhat difficult, but you can get them all by stomping two each time they stop spinning. Back at the planet, go down the pipe and pick up the first Spin Drill you see. Jump over the Digga and spin in the air so you don't get hit by it. You'll come out in an area with another Digga and Spin Drill in case you get hit. Spin in the right side of the dirt where the Digga is and you'll ricochet to the next area. Jump over the electric orb and go down the warp pipe. In the next area, grab the Spin Drill and go to the center of the room. You can get through each room by spinning when the electric orb or orbs are directly beneath you. At the bottom, take the orange warp pipe and break the crystal to use the Launch Star. At the Toad Ship, you'll get a checkpoint flag and the blue Toad will tell you you need to collect five silver stars to make one Power Star.
 * Second planet

This is a square planet with Diggas going around the outside of it and a bunch of hollow rooms on the inside. There is one silver star on the outside of the planet, but the rest can be found inside. It's somewhat maze-like, and due to the gravity, you'll need to plan out which way you enter the room to get the star.
 * Third planet

First off, jump off the left side of the platform and go along the planet dodging Diggas until you find a Spin Drill and the first silver star right after it. Continue over the corner to the next side of the planet and spin in the second dark circular patch of dirt between the red gates to get another silver coin. You can only go down at the bottom of this room, which puts you back to the left of the starting platform. This time you'll want to go all the way around past where you drilled last time to the other end of that side of the planet. Drill the similar spot (the second one from the edge) to grab another star and quickly jump on the Goomba down there before it attacks. Jump to the other side of this room across the platform with the Spin Drill to grab another star (remember not to spin while jumping). Go back to the other side where the Goomba was, and drill down directly over where you can barely see the top of the silver star bubble in the room below (right next to the platform with the Spin Drill). That's the last star, and it's on top of the planet. Drill down out of the room you're in and go around the outside, or drill through the edge at the small patch closest to the corner for a shortcut.

Digga-Leg's Daredevil Run (Prankster Comet)
This mission requires you to complete the boss battle from Digga-Leg's Planet with only one point of health. Avoid all of the yellow Diggas and don't get crushed by his legs when he's moving around the planet.

Green Stars
In the second planet, jump on the non-drillable platform and you'll see the first Green Star on top of the fence. Backflip onto the fence and backflip again to grab the star. On the third planet, go to the area where the Launch Star appears. The green star is located floating high above one of the disappearing platforms. You can get the star either by triple jumping across the disappearing platforms or just backflipping and spinning from the platform with the Launch Star.
 * Green Stars 1 or 2

In the interior of the second planet, you can't miss the Green Star since you come out right next to it in the second area. You need to get hit by the Drilla to lose your Drill Mario power, then wall jump from the wall you came out of to the Green Star.
 * Green Star 3