A wonderful introduction to the study of thermodynamics.

When the light atoms strike the dark, underside portions of four vanes located on top of the central spindle, these vanes start to spin up to 3,000 RPM within the low-friction, needlepoint bearing in a partial vacuum glass globe. Spinning under sunlight or an incandecent buld, the stronger the light the faster it will spin. Great for science and solar projects. Measures 5" x 3". No batteries or electricity required.