Similarities and differences in the heat flow from the Jovian planets—Jupiter, Saturn, Uranus, and Neptune—can all be understood with one model. The atmosphere of those four giant planets primarily controls the amount of heat that they radiate, said William B. Hubbard in remarks prepared for the American Physical Society meeting in Chicago, March 23. Hubbard is professor and head of the department of planetary sciences and director of the Lunar and Planetary Laboratory at the University of Arizona.