Active volcanoes are where cosmic sources of heat interact with a planetary body and result in liquid rock rising up out of the ground. And Jupiter’s moon Io has over a hundred active volcanoes. Each of these volcanoes glows in the dark. To me, who generally observes in the infrared, Io doesn’t so much resemble a pizza as a kind of giant firefly in the sky with bright glowing beads of light that sparkle and change.
Loki is the most powerful persistent volcano on Io. Its glow is the only constant on Io, being the only volcano that is always erupting brightly enough to be measureable from ground-based telescopes. It erupts seemingly periodically, but that period appears to have changed over time. And, every time we think we understand how Loki works, its behavior changes. What is the nature of Loki’s eruption? Are the brightening events due to the surface of a lava lake overturning?
The only volcanoes brighter than Loki are the outbursts: rare, short-lived, very bright events that dim in a matter of days. What type of volcanoes are the outbursts? What other volcanoes are erupting? For how long? How brightly? How long does a persistent volcano tend to stay active?
Io’s active volcanoes are the result of tidal heating. But, does the distribution of Io’s volcanoes tell us anything about Io’s interior and the tidal heating process? Comparisons are hampered by the lack of direct imaging of Io’s poles.