Jupiter's moons in fiction smallest of the four Galilean satellites and the second closest to Jupiter. It is theorized to have an ocean of liquid water underneath its icy surface; the thickness of the ice is much debated. The probable presence of the water ocean has made it a favored location for modern fictional speculation about extraterrestrial life in the Solar System. Ganymede is the third of the Galilean moons from Jupiter. It is the largest moon in the Solar System, bigger than the planet Mercury (though less massive), almost 52% larger than the diameter of the Moon and with twice its mass. It
Triton (moon) Triton, called "Triton Hopper", would mine nitrogen ice from the surface of Triton and process it to be used as small rocket propellant and fly or 'hop' across the surface. On 5 October 2017 Triton occulted the star UCAC4 410-143659. Triton (moon) Triton is the largest natural satellite of the planet Neptune, and the first Neptunian moon to be discovered. The discovery was made on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, an orbit in the direction opposite to its planet's rotation. At in diameter,