Imagery of stars and clouds onto a ceiling creates an ethereal, almost otherworldly atmosphere for a party or just for fun. Instead of painting the images in place or using decals, create the scene with a special star projector unit that also displays clouds. As an alternative, use a DVD projector aimed at the ceiling and loop your favorite video that features stars and clouds.
Not all star projectors are created equal. Some are designed to show actual constellations, projecting them planetarium-style all around the room thanks to an internal light source and tiny holes in the unit arranged to represent individual stars in the constellations. Others feature slides or image discs that display specific images on the wall or ceiling, while yet others provide an ever-changing array of stars with clouds of a different color for a mystical effect. Read up on any particular star projector you're considering for purchase to be sure it creates the desired effects beforehand.
DVD Projector Method
A DVD projector that plays standard DVDs can be used to project stars, clouds or fantasy outer space scenes featuring numerous stars, nebulae and galaxies. Purchase a DVD that has the desired imagery already recorded, or download a video that suits the task and burn it onto a DVD. Place the DVD in the projector and angle your DVD projector so the imagery shows on the ceiling. Prop the projector up in such as way that it is stable and still receives adequate airflow around any vented areas, so it does not overheat. A regular slide projector can be used in similar fashion, using static slide images in place of video imagery.