What common planetary feature seems to be absent on Io?
Venture a guess as to what may be the dominant process acting on this satellite. ANSWER Io displays prominent orange colors, with blackish mottled areas (that has reminded some of a giant pizza with olives). It may well be the most remarkable of all satellites, in that the surface is undergoing constant dynamic change, largely through volcanic processes. Astrogeologists have rated Io as the “most geologically active planetary body in the Solar System”, roughly 100x that of Earth on a surficial area basis. What they mean is that it is undergoing more volcanic eruptions, for its size, than any other planetary body (at least 16 volcanoes that are active have been detected on Io); besides Earth, it is the only other object with live volcanoes spewing hot lavas. Although the ionian surface generally has a temperature of -140° C, hot spots with temperatures up to 1600° C (2900° F) attest to volcanically active areas. Io’s surface is geologically young (no impact craters have been found on it
