Pele (volcano)

Pele is also notable for a persistent, large red ring circling the volcano resulting from sulfurous fallout from the volcanic plume.

As Voyager 1 approached the Jupiter system in March 1979, it acquired numerous images of the planet and its four largest satellites, including Io.

[5] This depression, later found to be the source of the Pele volcano, is at the northern base of a rifted mountain later named Danube Planum.

While processing images of Io to enhance the visibility of background stars, navigation engineer Linda Morabito found a 300-kilometre (190 mi) tall cloud along the moon's limb.

[7] When Voyager 2 flew through the Jupiter system in July 1979, its imaging campaign was modified to observe Io's plumes in action and to look for surface changes.

[9] Thermal emission from Pele was detected in nearly every occasion Io's trailing hemisphere was imaged while the moon was in the shadow of Jupiter.

[5] The volcanic plume at Pele was found to be intermittent or primarily composed of gas with occasional bursts of increased dust content.

[10] Subtle changes in the shape and intensity of the large red-ring plume deposit surrounding Pele were observed in daylight images of the volcano, with the most notable change seen in September 1997 when dark pyroclastic material from an eruption of Pillan Patera covered up a portion of Pele's plume deposit.

The cameras revealed a curved line of bright spots along the margin of the Pele patera (a term used for volcanic depressions on Io, akin to calderas).

[13] Volcanic activity at Pele, as seen in images taken by Galileo in October 2001 while Pele was on Io's night side, appears to be limited to small thermal "hot-spots" along the margins of the patera and a more intense thermal emission source within a dark area in the southeast portion of the patera floor.

[18] Variable activity in different portions of the Pele lava lake may also result in the changes in brightness and shape of the plume deposit over time observed by various spacecraft.