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<\/a><\/p>\nThe north polar region of Io was captured by NASA\u2019s Juno spacecraft on December 30, 2023. Image credit: NASA \/ JPL-Caltech \/ SwRI \/ MSSS \/ Gerald Eichst\u00e4dt.<\/p>\n
Jupiter\u2019s moon Io is the most volcanically active world in our Solar System.<\/p>\n
It is constantly stretched and squeezed by Jupiter\u2019s gravity, generating enormous amounts of internal heat.<\/p>\n
Until now, almost all observations of this heat came from infrared measurements that sense only the surface skin temperature.<\/p>\n
\u201cIo provides a unique window into learning how tidal heating works throughout the cosmos, a fundamental process that provides energy and heat to worlds that are far from their parent star,\u201d said Juno\u2019s principal investigator Dr. Scott Bolton, a researcher at Southwest Research Institute.<\/p>\n
\u201cThis process can not only create the most volcanic body in the Solar System, in the case of Io, but also fuels the subsurface oceans on the moons of giant planets, such as Europa and Ganymede.\u201d<\/p>\n
\u201cUp until this point we could only observe the heat escaping at the surface or through eruptions.\u201d<\/p>\n
\u201cNow we can characterize how the heat is moving from the interior toward the surface.\u201d<\/p>\n
To make the first-ever measurements of the temperature below the surface of Io, Dr. Bolton and his colleagues used data from the Microwave Radiometer (MWR) instrument on NASA\u2019s Juno spacecraft.<\/p>\n
These data allowed the team to see several meters below the surface, revealing a significant temperature increase \u2014 more than 20 degrees Celsius \u2014 in the upper few meters.<\/p>\n
The observations showed that Io\u2019s surface is smooth when viewed at long microwave wavelengths.<\/p>\n
The microwave signal also revealed that the upper layer of Io\u2019s surface has a low density compared to solid rock, similar to volcanic ash or pumice.<\/p>\n