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JWST spots the first known ‘steam world’

Beyond our solar system, this water world’s pressure may be creating funky forms of matter

An illustration of a blue, cloudy planet in front of a small red star.

The exoplanet GJ 9827d, shown in the foreground of this artist’s illustration, seems to be a “steam world” with an atmosphere full of water vapor.

NASA, ESA, Leah Hustak (STScI), Ralf Crawford (STScI)

By Lisa Grossman

This exoplanet’s atmosphere is going full steam ahead.

A planet beyond our solar system called GJ 9827d has an atmosphere composed almost completely of hot water molecules, astronomers report in the Astrophysical Journal Letters October 4.