Acala Fluctus

Acala Fluctus is a volcano with a diameter of 415.36 kilometers located on the moon Io, the most volcanic moon in the solar system orbiting Jupiter.^[1] It is the site of sporadic fire fountaining activity with variable high temperatures.^[2][3]

Image of Io from the Galileo spacecraft

History

Low-temperature spots were detected in 1979 by Voyager IRIS. In the late 1990s, the Galileo spacecraft detected a high-temperature hot spot over Acala Fluctus. Then Galileo also detected low-temperature hot spots on Acala Fluctus in the year 2000. Observations from Ground-based Infrared Telescopes showed that Acala Fluctus was active for ~18 months in the years 2019 and 2020. During that time it experienced two outburst with temperatures of ~1200 Kelvin.^[2]