Jupiter's moon Io is in sharp contrast to the other three Galilean moons. While Callisto, Ganymede and Europe all seem to have oceans below the ground, Io is a volcanic world covered with more than 400 active volcanoes. Io is actually the most volcanically active body in the solar system.
Io's largest volcano is called Loki, after a god in Norse mythology. It is the most active and powerful volcano in the solar system. Since 1979 we have known that it is active and that it is both continuous and variable. And since 2002, thanks to a research paper in Geophysical Research Letters, we have known that it breaks out regularly.
The first author in the 2002 paper was Julie Rathbun, who is now a senior scientist at the Planetary Science Institute. Now Rathbun has presented a poster about Loki at the American Astronomical Society's 51
st Annual Meeting of the Planetary Sciences Department. According to Rathbun, Loki is due to erupt again every day now.
Loki is large enough for Earth-based telescopes to see it. On the poster, Rathbun and the other author say J.R. Spencer said that between 1988 and 2000, Loki interrupted every 540 days. During about half of these days, Loki was light, while the other half Loki was darker in size. During the decade thereafter, observations were rare and there did not appear to be any periodicity for Loki's operations.
However, from 2013, Loki again showed periodicity. This time, there appeared outbreaks every 475 days for 160 days. What does all this mean?