K2-66b is a confirmed mega-Earth orbiting the subgiant K2-66, about from Earth in the direction of Aquarius. It is an extremely hot and dense planet heavier than Neptune, but with only about half its radius.
K2-66b is a mega-Earth with radius and mass . The planet's temperature is highly variable due to the variability of its host star, and is currently estimated at .
The planet orbits every 5.07 days at 0.06 AU. It orbits within a "photoevaporation desert", where orbiting exoplanets should be very uncommon. K2-66b's orbit is nearly circular.
The star, K2-66 is a G1 sub-giant in Aquarius. It has a sun-like temperature of 5887 K, which corresponds to its spectral class and is very close to that of the rotationally variable star Kepler-130. It has a radius of and a mass of . Its metallicity is âÂÂ0.047, and its apparent magnitude is 11.71.