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Using the Atacama Large Millimeter\/submillimeter Array (ALMA), astronomers were able to see Io as it passed into the shadow of Jupiter<\/a>, where sulfur dioxide gas freezes, falling out of the atmosphere of the Galilean moon.<\/p>\n \u201cWhen Io passes into Jupiter\u2019s shadow, and is out of direct sunlight, it is too cold for sulfur dioxide gas, and it condenses onto Io\u2019s surface. During that time we can only see volcanically-sourced sulfur dioxide. We can therefore see exactly how much of the atmosphere is impacted by volcanic activity,\u201d explained Statia Luszcz-Cook from Columbia University, New York.<\/p>\n Using this instrument, astronomers examined sulfur monoxide (SO) and sulfur dioxide (SO2) rising up from volcanoes<\/a>. Study of the data revealed volcanic releases constitute 30 to 50 percent of the atmosphere of Io.<\/p>\n As Io entered the shadow of Jupiter \u201cthe SO2 flux density dropped exponentially, and the atmosphere reformed in a linear fashion when re-emerging in sunlight, with a \u2018post-eclipse brightening\u2019 after \u223c10 minutes. While both the in-eclipse decrease and in-sunlight increase in SO was more gradual than for SO2, the fact that SO decreased at all is evidence that self-reactions at the surface are important and fast, and that in-sunlight photolysis of SO2 is the dominant source of SO,\u201d researchers describe in The Planetary Science Journal<\/em><\/a>.<\/p>\n The third, unexpected, gas was also found \u2014 potassium chloride (KCl).<\/p>\n \u201cWe see KCl in volcanic regions where we do not see SO2 or SO. This is strong evidence that the magma reservoirs are different under different volcanoes,\u201d Luszcz-Cook stated.<\/p>\n Like our own moon<\/a>, Io is tidally locked to its home planet, with one side always facing Jupiter. This condition, plus the gravitational tug of two of Jupiter\u2019s other large moons, Europa and Ganymede, pull on Io like taffy, creating heating within the moon.<\/p>\n This movement also creates large volcanoes<\/a>, like Loki Patera, which stretches 200 kilometers (124 miles) across the face of this Jovian moon.<\/p>\n Io, first seen by Galileo more than 400 years ago, continues to fascinate us today.<\/p>\n This article was originally published on <\/span><\/i>The Cosmic Companion<\/span><\/i><\/a> by <\/span><\/i>James Maynard<\/span><\/i><\/a>, founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat. You can read this original piece here<\/a>.<\/span><\/i>
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