"GJ 433 d is the nearest, widest and coldest Neptune-like planet ever detected," said Fabo Feng, lead study author and astronomer at the Carnegie Institution for Science. A multitude of exoplanets, especially terrestrial planets like Earth, have been found around red dwarf stars. They're smaller and cooler than our sun, and they're the most common star in our galaxy. Exoplanets tend to orbit closer to these stars and still be within the star's habitable zone, or the perfect distance for the planet to be temperate and potentially host liquid water on their surfaces.