The Galileo probe expanded on our knowledge of Jupiter's moon, Io, showing us just how hot and hellish the Jovian satellite could be.

On this date, Jan. 17, 2002, the Galileo probe made it’s 33 rd pass of Jupiter’s moon, Io. After Voyager 1’s pass in 1979, Io was dubbed the most volcanically active place in the solar system.

"We found the water in the equator to be greater than what the Galileo probe measured," said Cheng Li, a Juno scientist at the University of California, Berkeley. "Because the equatorial region is ...