Mons Huygens Moon further north, which was visited by Apollo 15. The tallest mountain known in the Solar System is in Rheasilvia crater on the asteroid Vesta, which contains a central mound that rises high; Olympus Mons on Mars is nearly the same height, at high. In comparison, Mount Everest rises to altitude above sea level (asl), but is only (base-to-peak) (btp). Africa's Mount Kilimanjaro is about altitude above sea level to the Uhuru peak; also 4.6 km base-to-peak. America's Denali, also known as "Mount McKinley", has a base-to-peak of . The Franco-Italian "Mont Blanc/Monte Bianco" is in altitude above sea level,
Solar System 7 light-years away. Compared to many 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 typical—both rocky and gas—so there is no "gap" as seen between the size of Earth and of Neptune (with a radius 3.8 times as large). Also, these super-Earths have closer orbits than Mercury. This led to hypothesis that all planetary systems start