A NASA spacecraft paid a rare visit to an old friend over the holiday weekend—the volcanic Jupiter moon of Io, reports NPR. The Juno craft made a close flyby, at just under 1,000 miles, for the first time in 20 years and captured new photos that NASA is posting here. NPR describes "a silhouetted, dusty red sphere pockmarked by massive grayish volcanoes." At IFL Science, Stephen Luntz writes that the "stunning" images "will be [pored] over for years to come." Juno has been in Jupiter's orbit for about seven years, but most of its focus has been on the planet itself—this new flyby zeroes in on Io. Another is scheduled for Feb. 3.
The moon's volcanoes in particular intrigue astronomers. "We are looking for how often they erupt, how bright and hot they are, how the shape of the lava flow changes, and how Io's activity is connected to the flow of charged particles in Jupiter's magnetosphere," says Scott Bolton, Juno's principal investigator, in a statement. Popular Science notes that Io is thought to be "the most volcanic world in our solar system." For context, Earth has roughly 50 eruptions a year, but the number on Io is believed to be 100 times greater. This was the closest flyby since one made by the Galileo craft in 2001. (More space exploration stories.)
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