This artist's concept allows us to imagine what it would be like to stand on the surface of the exoplanet TRAPPIST-1f, located in the TRAPPIST-1 system in the constellation Aquarius. NASA/JPL-Catlech

Hubble Suggests Outer TRAPPIST-1 Planets May Have Substantial Water

The planets that may contain water include the three worlds in the habitable zone, which caused a media stir when their discovery was announced earlier this year.