
Washington [US]: Computer simulations by Rice University scientists and their collaborators are the first to integrate a model of planet formation and evolution that explains two puzzling observations of exoplanets orbiting distant stars: the rarity of worlds about 1.8 times larger than Earth and the near-identical size of adjacent planets in hundreds of planetary systems.
One puzzle known as the "radius valley" refers to the rarity of exoplanets with a radius about 1.8 times that of Earth.