Since December 1978, the National Oceanic and Atmospheric Administration's polar - orbiting satellites have measured upwelling microwave radiation from atmospheric oxygen, and Spencer and Christy use this data to calculate the temperature of
broad volumes of the atmosphere.
The sheer
volume of discoveries would allow astronomers to begin comparing
broad classes
of exoplanets: learning how stellar flares affect planetary
atmospheres, for instance, or what sorts
of planets surround stars
of different ages.