which of jupiter’s moons is believed to be covered with water ice
Galilean moons Some models predict that there may have been several generations of Galilean satellites in Jupiter's early history. Each generation of moons to have formed would have spiraled into Jupiter and been destroyed, due to tidal interactions with Jupiter's proto-satellite disk, with new moons forming from the remaining debris. By the time the present generation formed, the gas in the proto-satellite disk had thinned out to the point that it no longer greatly interfered with the moons' orbits.[14][15] Other models suggest that Galilean satellites formed in a proto-satellite disk, in which formation timescales were comparable to or shorter than orbital migration timescales.[16] Io is anhydrous and likely has an interior of rock and metal.[14] Europa is thought to contain 8% ice and water by mass with the remainder rock.[14] These moons are, in increasing order of distance from Jupiter:
Atmosphere of Jupiter The atmosphere of Jupiter lacks a clear lower boundary and gradually transitions into the liquid interior of the planet.[3] From lowest to highest, the atmospheric layers are the troposphere, stratosphere, thermosphere and exosphere. Each layer has characteristic temperature gradients.[4] The lowest layer, the troposphere, has a complicated system of clouds and hazes, comprising layers of ammonia, ammonium hydrosulfide and water.[5] The upper ammonia clouds visible at Jupiter's surface are organized in a dozen zonal bands parallel to the equator and are bounded by powerful zonal atmospheric flows (winds) known as jets. The bands alternate in color: the dark bands are called belts, while light ones are called zones. Zones, which are colder than belts, correspond to upwellings, while belts mark descending gas.[6] The zones' lighter color is believed to result from ammonia ice; what gives the belts their darker colors is uncertain.[6] The origins of the banded structure and jets are not well understood, though a "shallow model" and a "deep model" exist.[7]