The Juno spacecraft captures the best image of Jupiter’s volcanic moon Io

March 6 () –

NASA’s Juno spacecraft passed near Io at an altitude of 51,570 kilometers on March 1, providing the best images yet of the colorful surface of this Jovian moon.

Shown in the foreground above are the Lei-Kung Fluctus, Amaterasu Patera, Dazhbog Patera, Surt & Vivasvant Patera volcanoes. The smallest visible detail is about 35 kilometers across, as explained by Andrew R. Brownmission scientist at the Southwest Research Institute (SwRI).

Most of the dark spots seen on Io’s surface are the result of volcanic eruptions. Among them is Eastern Girru, a dark spot not seen when Io was last observed with this resolution, during New Horizons’ encounter with Jupiter in February 2007.

Girru Oriental was experiencing a large eruption at the time, but hadn’t had time to produce a new lava flow before the end of the encounter, which lasted a week. This small flow field, measuring 3,200 square kilometers in size, may also have been reactivated during an eruption in October 2021, according to the spacecraft’s Jovian Infrared Auroral Mapper (JIRAM) instrument.

Another apparent surface change is at Chors Patera, which has undergone significant reddening since Galileo last observed it in October 2001. The reddish materials on Io are indicative of the presence of short-chain sulfur and are often associated with high temperature silicate volcanism. Other dark spots near the terminator, the boundary between Io’s day and night sides, are the shadows of high mountains. The dark spot in the center right in the upper right image may be due to a 5,500 meter high mountain.

The original JunoCAM observations were reprojected to a point perspective map projection and magnified 10 times to improve visibility of surface features. The original resolution of these images varied between 43 kilometers and 34 kilometers per pixel.

Io is the closest Galilean satellite to Jupiter. With a diameter of 3,600 kilometers, it is the third largest satellite, has the highest density of all satellites and, proportionally, the least amount of water among all known objects in the solar system. It was discovered by Galileo Galilei in 1610.