Kepler discovered the planet based on the star’s slight dimming as the planet passed in front, from the telescope’s perspective – a process of discovery called the transit method.
The next generation of large telescopes, such as Okayama 188-cm Reflector Telescope and the latest observational instrument MuSCAT used in this observation, are able to investigate the composition of the planet’s atmosphere.
Super-Earth K2-3d sits just 150 million light years away from Earth, and is one of the most likely planets we know of to host alien life.
During the Kepler mission about 20 potentially habitable exoplanets that also have transiting orbits were discovered. This makes K2-3d a special object for the scientists to observe, because of its close proximity and brighter appearance from a telescope placed on Earth.