Interactions of smaller spots with the Great Red Spot and with each other.
Auroral emissions in the polar regions, both in the ultraviolet (which were not present during the 1973 Pioneer encounter) and in the visible.
Cloud-top lightning bolts, similar to terrestrial superbolts, and meteoritic fireballs.
A temperature inversion layer in the stratosphere and a temperature of 160 K at the level at which the atmospheric pressure is 0.01 bar.
Very strong ultraviolet emission from the disk, indicating a thermospheric temperature of more than 1000 K.
A hot (1100 K) upper ionosphere on the dayside that was not observed by Pioneer 10, suggesting there may be large temporal or spatial changes.
An atmospheric composition with volume fraction of helium of 0.11 ± 0.03.
A substantially colder atmosphere above the Great Red Spot than in the surrounding regions.
Satellites and Rings
At least eight currently active volcanoes on Io, probably the result of tidal heating of the interior of the satellite, with plumes extending up to 250 kilometers above the surface.