With a mass of 1.8 Neptune masses and a radius of Jupiter, WASP-107b presents a challenge to planet formation theories. An artist’s impression of WASP-107b. Image credit: NASA / ESA / Hubble / M. Kornmesser. WASP-107 is a highly active K-type main sequence star located about 212 light-years away in the constellation of Virgo. First detected in 2017, WASP-107b is one of the least dense exoplanets known — a type that astrophysicists have dubbed...