Shifting hot spots on Jupiter’s volcano moon Io

New images show that the massive volcano Loki Patera on Jupiter’s moon Io has changed in the past two years.
By | Published: November 13, 2015 | Last updated on May 18, 2023
Io’s Loki Patera and its lava lake (the dark, horseshoe-shaped feature at center) posed for the Voyager 1 spacecraft in March 1979
If I had to choose one moon in the solar system as my favorite, Io would win easily. I’ve been fascinated with this world ever since the Voyager 1 spacecraft flew past Jupiter and its family of satellites in March 1979 — and revealed Io as the most volcanically active object in the solar system. In the 1970s, you needed a spacecraft to see Io’s volcanoes. No more. Advances in telescope and instrument technology have brought the distant moon into focus from Earth.

Case in point: Earlier this year, a team of astronomers detected changes in one of Io’s biggest volcanoes, Loki Patera. Team member Michael Skrutskie of the University of Virginia reported the discovery on Thursday at the 46th annual meeting of the Division for Planetary Sciences in National Harbor, Maryland.

The researchers observed Io with the Large Binocular Telescope (LBT) — twin 8.4-meter mirrors on a single mount that together have the resolving power of a single 75-foot (22.8m) telescope. They viewed Io at an infrared wavelength of 4.8 micrometers, which is optimal for picking up volcanic heat signatures, on a night when its neighboring moon Europa passed directly in front of Io.

This raw Large Binocular Telescope image of Io shows the fringes of Loki Patera — the bright spot — and other active volcanic areas.
Combined with the LBT’s exquisite resolution, the occultation allowed the scientists to see details just 1 to 2 miles (2 to 3 kilometers) across. The observations revealed two separate hot spots within the 125-mile-wide (200km) lava lake that surrounds the volcano. Interestingly, the spots didn’t match up with those the team saw in 2013, further proving the dynamic nature of Io.

With its continually changing landscape fueled by massive volcanic eruptions, Io seems in no danger of losing its status as my favorite moon.

Check out the rest of the LBT’s images of Io by visiting