Yoshi Star Galaxy

"I know! We should team up! Come on! Hop on my back!"

- Yoshi

Yoshi Star Galaxy is one of the many galaxies in the game Super Mario Galaxy 2. This is the first galaxy in which Yoshi is found; however, before Mario can break the Yoshi egg, he must defeat a Magikoopa to break the barrier surrounding the egg, making this galaxy the first and only one in which Yoshi cannot be accessed without a certain method. The galaxy itself consists of lush meadows, with many flowers, grassy paths and an active volcano.

Starting Planet
The player will land at the beginning of a path. The pathway ahead of the start goes uphill and is filled with many Piranha Plants, Octoombas, and prickly plants. Ahead after the pathway, there is a force field around a Yoshi's Egg on a nest guarded by a Magikoopa that uniquely, summons Mini Goombas. After it is defeated, the force field disappears and the Yoshi's egg can be cracked open to release Yoshi. Just up ahead of the egg's nest are some fruits and enemies that Yoshi can eat for Star Bits. To the left of the fruits is a small hill with a Comet Medal on top. There is a small waterfall with a rushing current nearby as well. To the right are several terraces of land which contain Crystals and Flipbugs. There is also a huge volcano, where the Launch Star appears after Yoshi eats the giant golden fruit. When blasting off from the Starting Planet, the volcano will erupt similarly to the volcano in Melty Molten Galaxy from the first game, except that this volcano has smoke. In the second mission, the majority of this area is infested with Lakitus and Spinies.

Earth Planet
After using the Launch Star from the first planet, Mario and Yoshi land on a tiny planet, where they can pass by a Checkpoint Flag. It has Crystals, insects, and a Chance Cube. One of the Crystals reveals a Launch Star, which Mario must take to travel to the next planet.

Tower Planet
On this planet, the player and Yoshi must climb the tall tower to reach the Launch Star. There are Piranha Plants and prickly plants which cover up most of the pathways, but can be eaten by Yoshi. At the top, there are Octoombas and a flower. Using his tongue, Yoshi can swing up to a tiny wooden orb (using the flower) with the Launch Star. This planet is almost physically identical to the Tower Planet in the Good Egg Galaxy in the first game, except for a bone-like platform at the bottom and a few blue springboards. This planet is also one of three planets that appears on the cover of Super Mario Galaxy 2.

Fossil Planet
After using the Launch Star from the Yoshi Tower Planet, the player and Yoshi will arrive on this large planet. The player will find a Checkpoint Flag shortly after landing. This planet is infested with Spranglers and Paragoombas. The player and Yoshi can navigate through the planet by jumping between the blocks, using the flowers, pulling moveable blocks, and using the moving platforms. By using the flowers, the player and Yoshi can reach the top area where the Power Star is trapped in a crystal.

Spiny Shooting Planet
During the second mission, the player and Yoshi will land on this planet after using the Launch Star from the main planet. Here, they can pass a Checkpoint Flag. Enemies here include a Lakitu and several Spinies which the Lakitu spawns. There are also three cages, two of them containing Star Bits, and the other containing a Luma which will transform into a Launch Star once it is set free. The cages can only be broken by having Yoshi eat and spit out a Spiny towards one of the cages.

Orbiting Planetoids
During the second mission, Mario and Yoshi can land on this planet if the player activates the Launch Star in midair while flying from the Spiny Shooting Planet. This area has a set of small, flat planetoids that are orbiting around a slightly larger spherical planet. These platforms contain a 1-Up Mushroom, a Life Mushroom, a few coins and some fruits. Mario and Yoshi can use the Launch Star on the planetoid located at the top to blast off to the next planet.

Marble Block Planet
During the second mission, the player will land on this planet where they must use Yoshi's tongue to pull out platforms to climb up. The player must also have Yoshi eat a Spiny and spit it out toward a cage with Launch Star inside to blast off to the final planet. Enemies here include a Lakitu and Spinies. There are also crystals containing Star Bits and a coin and the platforms that Yoshi can pull out contain a 1-Up Mushroom, coins, and Star Bits. There is also another 1-Up Mushroom on top of the planet, to get it the player should jump on the cage with Yoshi then flutter jump up to get it.

King Lakitu Planet
This is the final planet during the second mission. The player and Yoshi will land on this area after blasting off from the Marble Block Planet. Here, they can pass a Checkpoint Flag. Using Yoshi's tongue, they can swing up to the top area where King Lakitu is fought. There are two crystals on this planet, each with a coin inside of them. Should the player use the infinite Flutter Jump glitch towards the dark clouds in the background mid-battle, they would get electrocuted and fall into the abyss. Trying to infinite flutter away from the planet during a battle with King Lakitu results in the player losing a life.

Green Star 1
The first Green Star is found above a hill on the Starting planet, where the Comet Medal is located. The player must use Yoshi and a timed backflip to be able to reach the star.
 * Planets Visited

Green Star 2
During the Saddle Up with Yoshi mission, the player must obtain Yoshi and head to the area with the large, golden fruit. To the right of this object will be an indent in the mountain with the Green Star in plain sight. The player will need to simply Flutter Jump to the star to get it.
 * Planets Visited

Green Star 3
During the Saddle Up with Yoshi mission, the player should make their way to the top of the Fossil Planet. They should use the flowers at the top to move their way left where the Green Star is located. A timed backflip or using the infinite flutter glitch is needed to reach the star.
 * Planets Visited

Prima Official Game Guide description

 * "The Yoshi Star Galaxy is where Mario first meets Yoshi on his travels across the cosmos. With this faithful buddy at Mario's side, Bowser doesn't stand a chance. Yoshi loves to nosh on berries, baddies, and power-ups, so indulge Yoshi's rumbly tummy and reap the benefits."

Trivia

 * If the player plays as Luigi, it is possible to get through the whole galaxy without Yoshi using precise jumping, with the exception of the Golden Fruit, which the player cannot get rid of without Yoshi.
 * It is possible to enter the King Lakitu planet on the first mission, using the infinite flutter glitch. However, if the player tries to go back, they will lose a life.

Sternen-Yoshi-Galaxie Galassia Isola Yoshi