NASA Juno spacecraft discovers auroral ‘footprints’ of Jupiter’s moon Callisto

NASA’s Juno spacecraft has successfully found and characterised the auroral “footprints” of Jupiter’s moon Callisto for the first time.

This discovery completes the “family portrait” of auroral signatures from all four of Jupiter’s largest moons, known as the Galilean moons. These footprints reveal a lot about how the moons are “connected” to Jupiter.

Callisto’s footprint is hard to find because it is very faint and usually hidden or “buried” within Jupiter’s much brighter main auroral oval. This made it a huge challenge to detect.

In September 2019, a massive blast of solar wind from the Sun hit Jupiter’s magnetosphere. This caused Jupiter’s main auroral oval to temporarily shift toward the equator, away from its usual position. This provided a clear view of the area where Callisto’s footprint was located.

Juno’s observation confirmed that Callisto’s footprint has a double-spot structure, which is similar to the footprints of the other three Galilean moons. The spacecraft also took “in-place” measurements of the charged particles and magnetic fields associated with the footprint.

By confirming that Callisto’s footprint is created by the same kind of physical process as the other moons, scientists now have a complete picture of how all four of the major moons interact with Jupiter.

Getting a clear picture of Callisto’s footprints will help us understand more about the complex magnetic environment of Jupiter and provide valuable data for future missions, such as the European Space Agency’s JUICE mission, which is on its way to Jupiter.

The NASA Science article stated that, “This discovery finally confirms that all four Galilean moons leave their mark on Jupiter’s atmosphere, and that Callisto’s footprints are sustained much like those of its siblings, completing the family portrait of the Galilean moon auroral signatures.”

What is the Juno mission of NASA?

Juno’s mission is to measure Jupiter’s composition, magnetic field, gravitational field, and polar magnetosphere.