AstroBKK

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Jupiter’s diameter is 142,800km, which is ~11.3 Earths radii for a mass equivalent to 320 Earths. It comprises mainly hydrogen (90%) and helium (10%), and other minor components (ammonia, water, sulfides, phosphine, nitrogen, noble gases and hydrocarbons such as methane and acetylene). Its average density is 1.3.

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The characteristics bands appearance of Jupiter lies from a complex cloud structure present in the troposphere. With a thickness of 50km above the surface (defined as having a pressure of 1 bar), it contains:

• Zones, which are light areas where the gases rises, white and cold clouds containing ammonia ice.

• Belts, which are colored areas where the gases sink, with reddish brownish shades by various chemicals such as ammonium hydrosulfide and possibly organic chromophores.

Contiguous zones and belts move in opposite directions from powerful jet streams up to 600km/h, and their boundaries bands are the place of huge turbulence bands.

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Other distinctive features are storms. Known since the 16th century, the biggest one is the Great Red Spot with a diameter equivalent to two Earths. Its color may arises from the formation of compounds between acetylene and ammonia under ultraviolet radiation from the Sun. Recent studies indicates that the Great Red Spot is shrinking.

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