Formation and evolution of the Solar System owe its substantially lower mass simply to having formed a few million years after Jupiter, when there was less gas available to consume. T Tauri stars like the young Sun have far stronger stellar winds than more stable, older stars. Uranus and Neptune are thought to have formed after Jupiter and Saturn did, when the strong solar wind had blown away much of the disc material. As a result, those planets accumulated little hydrogen and helium—not more than each. Uranus and Neptune are sometimes referred to as failed cores. The main problem with formation theories for these planets is the
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