The erratic and flaming moon of Jupiter Following yet another extremely near flyby, NASA’s Juno probe has captured detailed images of Io, including a few volcanoes.

On February 3, Juno, an orbiting spacecraft that has been circling Jupiter for 38 days since 2016, made a close flyby of Io, traveling as near as 930 miles (1,500 kilometers). It follows a similarly close flyover on December 30, 2023, which resulted in the return of amazing close-up photos.

NASA claims that the two flybys are the closest any spacecraft has been near Io in more than 20 years.

Io is a moon of Earth, slightly bigger than it is, with a rocky surface and a hazy atmosphere of sulfur dioxide. Its two most notable features are the enormous volcanic depression known as Loki Patera, which is home to an ocean of magma, and the Pele volcano.

With eruptions considerably greater than those of Earth, Io is the most volcanically active planet in the solar system. Its orbit around Jupiter is the primary cause.
With an orbital period of just 42 days, Io is the innermost of Jupiter’s four so-called Galilean moons, along with Ganymede, Callisto, and Europa.

Massive heat and frictional tidal heating are produced by the gas giant planet’s and its other massive moons’ gravitational pull. High levels of volcanic activity are caused by this heat, and underneath the stony surface is an ocean of magma.

Two possible plumes—possibly of sulfur and sulfur dioxide—can be seen in the image above while they are being released from one or more of Io’s numerous volcanoes.

On March 7, Juno is slated to conduct its 59th perijove, or close flyby of Jupiter, in order to continue its exploration of the planet. In order to investigate the cloud tops up close, Juno’s elliptical orbit takes it far from Jupiter during each perijove and then swings it back to within a few thousand miles of the planet’s poles.

The Juno mission is the first to complete a full orbit around an outer planet.
Juno has a titanium radiation vault to shield its delicate scientific instruments, which include a microwave radiometer, a magnetometer, and a gravity science system, from Jupiter’s strong radiation belts. They aid in the measurement of Jupiter’s temperature, pressure, and composition as well as its magnetic and gravitational fields.