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
The Science of Aliens possibilities for alien life. The second section explores the variety of life on Earth and the extreme conditions in which it can survive. It looks at recent missions to moons and planets in the Solar System and what they can tell us about alien life before going on to examine some extra-solar planets. The next section presents two fictional planets, Aurelia and Blue Moon and their ecosystems as imagined by scientists. These are used to explore the factors and parameters governing life on other planets and are presented as two large interactive landscapes. The exhibition concludes by looking at the