Transcript: It’s particularly important to consider the possibility of life on or in the gas giant planets of the solar system because these are the type of planets that have been found around nearby stars. Over a hundred extrasolar planets are now known, and most of them are Jupiter-like or larger, although they are on tight orbits of their parent stars and are at higher temperatures. It will take a decade or more before Earth-like extrasolar planets are found in significant numbers. The gas giant planets are unlikely environments for life. They are just like the Sun in chemical composition with primarily hydrogen and helium. Even if they have rocky cores, the conditions close to the rocky core will be extremes of temperature and pressure that make it implausible for biological life to survive. There has been speculation that in the atmospheric regions of these gas giant planets, a moderate temperature is reached at some elevations, say, a hundred kilometers into Jupiter’s atmosphere. Carl Sagan speculated about life forms circulating in the atmospheric regions of Jupiter. However, the vertical currents of air in Jupiter’s atmosphere are extreme and it’s almost implausible that any buoyant organism could exist and be stable for a significant length of time. Thus, most astronomers think that life on or in the giant planets of the solar system in very unlikely.