"When Dr. Cosmic's class meets Commander Nova, the school astronomer, they know their next lesson will be out of this world! With the help of Dr. Cosmic's latest invention--a planetarium--the class must complete four challenges. Each time the planetarium shifts and the atmosphere changes, the students find themselves floating from planet to planet. They put their new magnetic antigravity belts and trusted handbooks to the test to figure out where in the solar system Dr. Cosmic's invention has 'sent' them--and how to land safely back on Earth."-- Provided by publisher.