WASP-39b is an extrasolar planet “Hot Saturn” discovered in 2011 by the WASP project notable for containing a substantial amount of water in its atmosphere. 1 2 3 4 WASP-39b is in the constellation of Virgo, and is about 700 light-years from Earth.

WASP-39b has a mass of about 0.28 times that of Jupiter and a radius of about 1.27 times that of Jupiter. The exoplanet orbits WASP-39, its host star, every 4 days. Hot water molecules were found in the atmosphere of WASP-39b in a 2018 study.

WASP-39b is also notable for its low density, close to that of WASP-17b, the least dense exoplanet known. While WASP-17b has a density of 0.13 ± 0.06 g/cm³, WASP-39b has a slightly higher density of 0.18 ± 0.04 g/cm³.


Observations of WASP-39b

Collaborative projects