NASA's Galileo spacecraft has found an "ocean" of molten or partially molten magma beneath the surface of Jupiter's volcanic moon Io, U.S. researchers say.
The finding -- from research conducted by scientists from the University of California, Los Angeles, UC Santa Cruz and the University of Michigan-Ann Arbor -- is the first direct confirmation of such a magma layer on Io, and explains why the moon is the most volcanic object known in the solar system, a UCLA release said Thursday.
"Scientists are excited that we finally understand where Io's magma is coming from and have an explanation for some of the mysterious signatures we saw in some of Galileo's magnetic field data," Krishan Khurana, a research geophysicist with UCLA's Institute of Geophysics and Planetary Physics said. "It turns out Io was continually giving off a 'sounding signal' in Jupiter's rotating magnetic field that matched what would be expected from molten or partially molten rocks deep beneath the surface."
The signal was detected by a magnetometer on the Galileo spacecraft.
Io's volcanoes are the only known active magma volcanoes in the solar system other than those on Earth, producing about 100 times more lava each year than all of Earth's volcanoes.
Unlike Earth's volcanoes that occur in localized hotspots like the "Ring of Fire" around the Pacific Ocean, Io's volcanoes are distributed all over its surface because of the global magma ocean lying about 20 to 30 miles below Io's crust, the researchers said.