This moving science gadget is like having a galaxy right on your desk — watch in amazement as the planets flip and rotate around endlessly! Made of metal and plastic, it makes a great conversation piece and decoration for space themed parties. Measures about 10 inches tall and 9 inches wide. Ideal decoration for home, office, or classroom. Fun and useful gift for those who are interested in learning about magnets and physics. Once the gadget is assembled, all it takes is one push and the "galaxy" will continue to rock back and forth until the battery needs to be replaced. Powered by one 9 Volt battery (not included). The small "planets" are 0.48" in diameter, and the large one in the center measures 0.94" in diameter.