The faraway exoplanet could help provide answers as to why there are hardly any planets with twice the diameter of Earth.

It consists of two planets orbiting a star similar to our Sun: K2-360 b: An ultra-short period "super-Earth" - a rocky planet larger than Earth but smaller than Neptune - about 1.6 times the size ...

Their model explains this gap by predicting that planets smaller than 1.8 times the Earth's radius are mostly rocky super-Earths, while larger ones are water-rich mini-Neptunes, aligning closely ...