Here is the full list of all 8 Gravity Mastery achievements.
Stay airborne for 30 consecutive seconds.
Acquire a gold star.
Gold star a level without jumping.
Acquire a gold star for level 1 without picking up an object.
Pick up a fast moving object.
Acquire a gold star for every level.
Complete the final level of the campaign without skipping any prior levels.
Complete the final level of the game.