Nasa's Juno Reveals Io's Hidden Thermal Secrets

WHO:

NASA - The organization responsible for the Juno mission.

WHAT:

NASA - The Juno mission has provided the first measurements of the temperature below the surface of Jupiter's moon Io.

NASA - Significant heating has been revealed within the shallow subsurface of Io, the most volcanically active world in the solar system.

NASA - Data collected during two close flybys shows that most of Io's surface is remarkably smooth and composed of material with very low density.

WHERE:

NASA - The observations were made on Jupiter's moon Io.

WHEN:

NASA - The data was collected during two close flybys, specifically mentioning Perijove 57 on December 30, 2023.

HOW:

NASA - The measurements were taken using the Microwave Radiometer (MWR) instrument aboard the Juno spacecraft, which can penetrate between about 6 and 12 miles below the surface using low-frequency microwave channels (0.6 and 1.25 gigahertz).

(UPDATED July 22, 2026 18:21 UTC)

NASA's Juno mission has made groundbreaking discoveries by providing the first measurements of temperature beneath the surface of Jupiter's moon Io, revealing significant heating in its shallow subsurface. The data, collected during two close flybys, including Perijove 57 on December 30, 2023, shows that most of Io's surface is surprisingly smooth and made up of low-density material. These measurements were taken using the Microwave Radiometer instrument aboard the Juno spacecraft, which can penetrate between six and twelve miles below the surface with low-frequency microwave channels.