Jupiter and Its Galilean Moons


Eleven times Earth’s diameter, Jupiter is a gas giant composed mostly of hydrogen and helium. It rotates rapidly on its axis, once every 10 hours. Jupiter’s famous Great Red Spot, a storm that has raged for 300 years, is tinted red by organic molecules and rotates counterclockwise with winds up to 270 miles per hour. Its cloud tops are five miles higher than the surrounding cloud layers. Jupiter has white ammonia (NH3) clouds, brown ammonium hydrosulfide (NH4SH) clouds, and water vapor (H2O) clouds. The prominent brown cloud band north of the equator is called the North Equatorial Belt. Lightning on Jupiter can disassociate small amounts of atmospheric methane (CH4), creating carbon soot that compresses into diamond hail as it falls through Jupiter’s deep atmosphere.