Space photo of the week: Jupiter's seething volcano moon gets a close-up

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Jupiter's moon Io, the most volcanic world in the solar system, was imaged from just 7,260 miles away.

Jupiter's moon Io as seen by Juno on Oct. 16, 2023.
Jupiter's moon Io as seen by Juno on Oct. 16, 2023. (Image credit: NASA/JPL-Caltech/SwRI/MSSS/Brian Swift © CC BY)

What it is: Io, Jupiter's third-largest moon

When it was taken: Oct. 15, 2023

Also published is a compilation of Juno's images of Io taken on Oct. 16, as well as another photo showing both Io and Jupiter in the same field of view.

Io is the fifth most distant moon from Jupiter, orbiting at an average distance of 262,000 miles (422,000 kilometers), and the third-largest Jovian moon, at slightly larger than Earth's moon, according to Space.com. (It's smaller than Ganymede and Callisto, but bigger than Europa.)

Io is covered in volcanoes, with about 100 times greater volcanic activity than Earth's, according to NASA. The cause is tidal friction; Io is tidally locked to Jupiter, always showing the planet the same side, yet its orbital path is elliptical because of the gravitational pull of both Europa and Ganymede, according to NASA. As Io bulges in and out, the friction creates heat.

The images, taken by the spacecraft's two-megapixel JunoCam, are the highest-resolution photos of Io since NASA's Galileo orbiter was in the Jovian system in 2001. During its mission, Galileo photographed two tall volcanic plumes from the moon's Pele and Tvashtar Catena volcanoes.

Juno is on the cusp of two even closer passes of Io. The spacecraft will make its 57th and 58th closest approaches, or perijoves (close passes), of Jupiter on Dec. 30, 2023, and Feb. 3, 2024, when it will get within just 930 miles (1,500 km) of Io's surface.

Jamie Carter
Jamie Carter
Live Science contributor

Jamie Carter is a Cardiff, U.K.-based freelance science journalist and a regular contributor to Live Science. He is the author of A Stargazing Program For Beginners and co-author of The Eclipse Effect, and leads international stargazing and eclipse-chasing tours. His work appears regularly in Space.com, Forbes, New Scientist, BBC Sky at Night, Sky & Telescope, and other major science and astronomy publications. He is also the editor of WhenIsTheNextEclipse.com.