Compared to other planetary systems the Solar System stands out in lacking planets interior to the orbit of Mercury. The known Solar System also lacks super-Earths (Planet Nine could be a super-Earth beyond the known Solar System). Uncommonly, it has only small rocky planets and large gas giants; elsewhere planets of intermediate size are typicalâboth rocky and gasâso there is no gap as seen between the size of Earth and of Neptune (with a radius 3.8 times as large).