structural:expansion, information:classification
Atmospheres

Atmospheres have been detected around several exoplanets. The first to be observed was HD 209458 b in 2001.

As of February 2014, more than fifty transiting and five directly imaged exoplanet atmospheres have been observed, resulting in detection of molecular spectral features; observation of day–night temperature gradients; and constraints on vertical atmospheric structure. Also, an atmosphere has been detected on the non-transiting hot Jupiter Tau Boötis b.

In May 2017, glints of light from Earth, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in the atmosphere. The technology used to determine this may be useful in studying the atmospheres of distant worlds, including those of exoplanets.