Colonization of the outer Solar System of the four Galilean moons. Despite this, its volcanoes could be energy resources for the other moons, better to colonize. The Artemis Project proposed a plan to colonize Europa. Scientists would inhabit igloos and drill down into the Europan ice crust, exploring any subsurface ocean. The report also discusses use of air pockets for human habitation. Ganymede is the largest moon in the Solar System. Ganymede is the only moon with a magnetosphere, but it is overshadowed by Jupiter's magnetic field. Ganymede receives about 8 rem of radiation per day. Due to its distance from Jupiter's powerful radiation belt, Callisto
Orbit or within that planet. Owing to mutual gravitational perturbations, the eccentricities of the planetary orbits vary over time. Mercury, the smallest planet in the Solar System, has the most eccentric orbit. At the present epoch, Mars has the next largest eccentricity while the smallest orbital eccentricities are seen with Venus and Neptune. As two objects orbit each other, the periapsis is that point at which the two objects are closest to each other and the apoapsis is that point at which they are the farthest. (More specific terms are used for specific bodies. For example, "perigee" and "apogee" are the