From the product description
This unique, eye-catching model depicts celestial gravitation and comes complete with four spheres, Saturn, Jupiter, Mars and the Moon. Just place the planet of your choice directly below the gravitational source and watch it float and spin in mid-air. The Gravitator glows beautifully in the dark, creating a radiant nighttime conversation piece or a handsome nightlight, while the Antique Gold frame will embellish any desk, table or bookcase.
Here's a link to the Galileo Gravitator with four floating planets