Eternal level 1:
In Make a Star 4, get your katamari to 1m31cm before time expires.

Eternal level 2:
In Make a Star 8, get your katamari to 25m1cm before time expires.

Eternal level 3:
In Make the Moon, get your katamari to 800m1cm before time expires.

Secret movie:
Finish Make the Moon, then make another moon and turn it into star dust.

Beat each level under the time limit to Unlock the following Comets:

Thanks to Revolution readers Danny Blane, Arctic Fox, SLdjFX, Seth, Candy, and Dancing_fool!