These are big hollow stars. Finding these are the key to winning the level. Spin when near them (you may have to jump) and you will be launched somewhere else. Sometimes you may find star bits cruising alongside you, so collect them with the pointer. Sometimes you have to collect five yellow star chips to get the launch star. While you're flying, you will see a blue line along the path of it. Use this as a guide to see where the launch star will take you to.
A Sling Star is a smaller Launch Star that takes you a lesser distance.
These small blue stars are found in air and in a chain. Point at one with the pointer and press to be pulled towards it. If you let go of while you are being pulled you will remain in the bubble and keep moving though slowing down. Like the launch star it can be broken into chips, which are blue. The blue star chips sound differently than the yellow ones. They have higher pitched voices.