Rocky planets orbiting red dwarf stars are appealing targets for astronomers since they are both common and easier to study than other planet varieties. One long-standing question is whether such planets can host atmospheres, since they experience a harsh environment of stellar flares and particle winds.

A team of astronomers calculates that NASA’s upcoming James Webb Space Telescope could potentially detect signs of an atmosphere in just a few hours of observing time. Since the presence of an atmosphere would lower the observed temperature of the planet’s dayside, relative to bare rock, a world with an atmosphere would have a distinct heat signature.

Although the technique works best for planets too hot to be in the habitable zone, it could have important implications for habitable-zone worlds. If astronomers find that hot, rocky planets can preserve an atmosphere, then cooler planets should be able to as well.

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