Hang space-related holiday tree ornaments from the chandelier. You can mix and match ornaments of different stars or hang the different planets from the chandelier bars.
Weave a space-related garland made of bendable, metallic-wrapped wire around the chandelier to form a wreath of sorts around the chandelier frame. Your garland can feature stars, planets, rockets or spaceships, for example.
Purchase miniature lamp shades that fit over the bulbs. The shade should be all white, or can feature space-themed designs, such as stars, comets and planets.