Io eruption captured by Juno

NASA has dropped a bunch of images from its Juno spacecraft’s latest fly-by of Jupiter’s volcanic moon Io, with one showing an eruption.

The image, released at the end of December but snapped by Juno in October, shows the large volcano Prometheus belching a plume of material on the moon’s dark side.

This JunoCam image of Jupiter’s moon Io captures a plume of material ejected from the (unseen) volcano Prometheus. Indicated by the red arrow, the plume is just visible in the darkness below the terminator (the line dividing day and night). The image was taken by NASA’s Juno spacecraft on October 15. Credit: NASA/JPL-Caltech/SwRI/MSSS

And on Saturday, Juno flew within 1,500km of Io, completing a sequence of two flybys that were the closest any spacecraft has come to the moon in 20 years.

Io artistic
Credit: NASA / SwRI / MSSS / Jackie Branc

Together, these passes have produced a “firehose” of information that Juno’s mission investigators are hoping will illuminate understanding of the world.

Of Jupiter’s four largest moons – known as the Galilean moons – Io is the only one with volcanic activity. The others – Ganymede, Callisto and Europa are frigid worlds that are potential life-supporting sites in our solar system.

Io on the other hand, is a hostile world of erupting landforms thanks to the competing gravitational pulls of Jupiter, Ganymede and Europa, and ionising radiation trapped by Jupiter’s immense magnetosphere.

Jnce 2024034 58c00029 v01 mapprojected
Credit: NASA / SwRI / MSSS

Understanding this violent moon is part of Juno’s current research.

“By combining data from this flyby with our previous observations, the Juno science team is studying how Io’s volcanoes vary,” says the mission’s principal investigator, Scott Bolton. of the Southwest Research Institute in San Antonio, Texas. “We are looking for how often they erupt, how bright and hot they are, how the shape of the lava flow changes, and how Io’s activity is connected to the flow of charged particles in Jupiter’s magnetosphere.”

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