Astronomers Observe that Io Glows

July 8, 2000   In the February 1999 issue of Discover magazine, it is reported that one of Jupiter's moons, Io, glows and thus does not simply reflect light, as is thought to always be the case for moons. This is illustrated below, where the left picture shows a picture of Io in darkness -- taken with the Galileo spacecraft. The right picture shows Io in normal light, with reference markings. Article. (Please note that these links sometimes expire.)

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