A Striking Crater on Jupiter’s Moon Ganymede

This look at the complex surface of Jupiter’s moon Ganymede came from NASA’s Juno mission during a close pass by the giant moon in June 2021. Image data: NASA/JPL-Caltech/SwRI/MSSS. Image processing by Thomas Thomopoulos © CC BY

This look at the complex surface of Jupiter’s moon Ganymede came from NASA’s Juno mission during a close pass by the giant moon in June 2021. At closest approach, the spacecraft came within just 650 miles (1,046 kilometers) of Ganymede’s surface.

Most of Ganymede's craters have bright rays extending from the impact scar, but about 1 percent of the craters have dark rays.  This image taken by JunoCam during the close Ganymede pass shows one of the dark-rayed craters. The crater, named Kittu, is about 9 miles (15 kilometers) across, surrounded by darker material ejected during the impact that formed the crater.  Scientists believe that contamination from the impactor produced the dark rays.  As time passes, the rays stay dark because they are a bit warmer than the surroundings, so ice is driven off to condense on nearby colder, brighter terrain.

Ganymede is the largest moon in our solar system, larger even than the planet Mercury. It’s the only moon known to have its own magnetic field, which causes auroras that circle the moon’s poles. Evidence also indicates Ganymede may hide a liquid water ocean beneath its icy surface.

Citizen scientist Thomas Thomopoulos created this enhanced-color image using data from the JunoCam camera. The original image was taken on June 7, 2021.

A View of Crescent Jupiter from Juno
A View of Crescent Jupiter from Juno.:Image data: NASA/JPL-Caltech/SwRI/MSSS
Image processing by Kevin M. Gill © CC BY­­

If you could ride along with NASA’s Juno spacecraft as it approaches Jupiter during one of its regular close passes by the giant planet, you would be treated to a striking vista similar to this one.

Unlike the Moon or Venus, this view of Jupiter in a crescent phase is impossible to see from Earth, even using a telescope. Since Jupiter’s orbit is outside Earth’s, an observer on Earth can only see the side of Jupiter that is illuminated by the Sun, so the planet always appears full.

Citizen scientist Kevin M. Gill created this mosaic using raw data from the JunoCam instrument. It comprises seven images taken during Juno’s 39th close pass by Jupiter on Jan. 12, 2022.

JunoCam's raw images are available for the public to peruse and process into image products at https://missionjuno.swri.edu/junocam/processing.  More information about NASA citizen science can be found at https://science.nasa.gov/citizenscience and https://www.nasa.gov/solve/opportunities/citizenscience.

More information about Juno is at https://www.nasa.gov/juno and https://missionjuno.swri.edu. For more about this finding and other science results, see https://www.missionjuno.swri.edu/science-findings.