Io is the most volcanically active object in the solar system. They have also revealed the effects of freezing of its shadow on the moon’s volcanic gasses, during the eclipses that occur daily.
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This research is the first time scientists have observed this phenomenon directly, improving our understanding of this geologically active moon.
Io’s atmosphere consists primarily of sulfur dioxide (SO2) gas emitted by volcanoes.
Io leaves Jupiter’s shadow after 1.7 Earth days, which is 2 hours of Io’s day, and the sulfur dioxide sublimates – goes straight from solid to gas – and pumps up the atmosphere once again when the moon re-enters sunlight.
“This confirms that Io’s atmosphere is in a constant state of collapse and fix, and shows that a large fraction of the atmosphere is supported by sublimation of SO2 [sulphur dioxide] ice”, said one of the team, John Spencer. This was achieved by combining observations made by the Spectrograph from Texas Echelon Cross Echelle and the Gemini North eight-metre telescope located in Hawaii.
Perhaps the most exciting part of all is that most of Jupiter’s 67 known moons – and the punishment the gas giant unleashes on them – remain a mystery to us.
In sunlight, Io’s surface averages out to minus 235 degrees F (minus 150 degrees C), but once the moon passes into Jupiter’s shadow, that temperature drops to minus 270 degrees F (minus168 degrees C). Once the moon moves out of the eclipse, the ice warms and the volcanic gas rebuilds the atmosphere.
NASAScientists have long wondered why Jupiter’s upper atmosphere is so hot. When the eclipse ends, the ice warms and the atmosphere reforms through sublimation.
This clockwork cycle of atmospheric collapse and rebirth has been speculated about for years, but Jupiter’s shadow renders Io too dark to study with today’s optical telescopes.
Tsang and Spencer’s observations occurred over two nights in November 2013, when Io was more than 420 million miles (675 million km) from Earth. Using the TEXES instrument, however, researchers were able to measure heat radiation from the moon. On both occasions, Io was observed moving in and out of Jupiter’s shadow, for a period about 40 minutes before and after eclipse.
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This July 10, 2016, image released by NASA was taken by the Juno spacecraft, five days after it arrived at Jupiter. Bright blue glows mark the sites of dense plumes of volcanic vapor. Its volcanos contribute to its atmosphere. If it turns out to be a full eclipse then the Io’s atmosphere collapses completely. “This tells us that planet-wide heating is a plausible explanation for the ‘energy crisis, ‘ a problem in which upper-atmospheric temperatures are measured hundreds of degrees hotter than can be explained by sunlight alone”.
