World 1 (Super Mario Galaxy 2)

World 1: The Great Space Journey Begins is the first world featured in Super Mario Galaxy 2. It is cloud-themed and seems to be located in the skies above Earth. It holds seven galaxies, the last of which, Bowser Jr.'s Fiery Flotilla, features the first encounter with Bowser Jr., who sends Gobblegut to attack Mario.

Music
The music that plays on the World 1 map is initially the same as the music for World 2. However, after Mario has collected at least 120 Power Stars, the music becomes a quiet, slowed-down rendition of the theme from the Good Egg Galaxy. The music is also different when Starship Mario first appears on the map.

Names in other languages
Welt 1 (Super Mario Galaxy 2) it:Mondo 1: Il Grande Viaggio nello Spazio