Discovery of 55 Cancri e

55 Cancri e is an exoplanet orbiting the Sun-like star 55 Cancri A, about forty light-years from Earth in the constellation Cancer. It is a super-Earth, a rocky world with a radius almost twice Earth's and a mass about eight times Earth's, which orbits so close to its star that its year lasts less than eighteen hours. Its surface is thought to be extremely hot, hot enough to melt rock and possibly form lava oceans on the star-facing side. The planet was first found by radial velocity measurements, and its transit across the star was detected later, which allowed astronomers to measure its size. Observations with the Spitzer and James Webb space telescopes have given hints about its heat distribution and possible atmosphere.

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