Melty Molten Galaxy

The Melty Molten Galaxy is a galaxy in Super Mario Galaxy, and the last galaxy to be unlocked in a dome. It is quite a large galaxy, made completely of lava and rock, and is situated between two stars, a red one and a light purple one. There's many Launch Stars here, allowing Mario to traverse the massive planet. There are also some small planetoids around it.

The Sinking Lava Spire
Mario starts out in the fire cauldron area, which he has to cross completely and get to the Launch Star at the top of the volcano. Mario can let himself fall into the volcano at this point, where he can get many Star Bits. As Mario leaves the volcano, it erupts. On little sphere capsules in the sky over the lava planet Mario meets a Hungry Luma. He has to use Pull Stars to get around miniature suns on his way through the sky. He then returns to the planet and has to search Star Chips to get to the Lava Spire, a mountain which begins to sink. Mario then must get to the top of the mountain quickly and smash the crystal to gain the Power Star.

Through the Meteor Storm
In this mission, meteors are constantly falling from the sky. Mario must constantly avoid them or they will burn Mario. Near the end of the mission, a part similar to Rolling Green Galaxy must be completed where Mario must ride a Star Ball to the end of a lava covered course. Ones Mario is at the end of the course the Star Ball will break giving Mario the Power Star.

Fiery Dino Piranha
In this level, Mario must battle a fiery version of the first boss Dino Piranha. The fiery version is faster, and Mario is only able to hit its tail when it is not on fire, which gets increasingly difficult because the flame goes out quicker and makes a flaming trail after a couple of hits.

Lava Spire Daredevil Run
This is the comet mission for Melty Molten Galaxy. Unlike most though, Mario does not fight a boss in this mission but must complete the entire "The Sinking Lava Spire" mission under the Daredevil Comet rules.

Red-Hot Purple Coins
Mario must collect 100 Purple Coins on the main planet. There is no time limit.

Burning Tide
Mario must feed a Hungry Luma 80 Star Bits to get to a new planet where there are 5 Silver Stars he must collect. The islands on the planet are sinking and the player must stay in the higher areas until the lava level lowers and it's safe to walk to the next part. Then, once Mario has gotten all 5 Silver Stars, they transform into a Power Star. This star is located in a lower area of ground, so Mario must wait until it is safe to grab the Star.