Saturn's moon Encedalus may have 'curtain eruptions' instead of jets

The odd glowing appearance of the surface activity on Encedalus may indicate curtain eruptions rather than individual jets of water vapor.
By Kathy Fey | May 07, 2015
New evidence regarding the nature of the eruptions on Saturn's moon Encedalus indicates that the vaporous eruptions on the moon's surface may be taking the form of long curtains of vapor rather than discreet jets.

According to Astronomy Magazine, recent analysis of data sent from NASA's Cassini spacecraft suggests that what appeared to be individual jets of vapor along the length of fissures on the moon's surface may in fact be "phantoms created by an optical illusion."

"We think most of the observed activity represents curtain eruptions from the 'tiger stripe' fractures, rather than intermittent geysers along them," Joseph Spitale of the Planetary Science Institute said. "Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets."

In most of Cassini's images of eruptions on Encedalus, a background glow is apparent, sometimes in a way that appears to be superimposed with images of vapor jets. The researchers looked at models showing the eruptions as long curtains running the length of the fractures, and found that the background glow effect as is seen in Cassini's images can be created when viewing such curtain eruptions through "folds" in the sheets of vapor.

"The viewing direction plays an important role in where the phantom jets appear," Spitale said. "If you rotated your perspective around Enceladus' south pole, such jets would seem to appear and disappear."

It appears that what seemed at first to be vapor jets are instead views of folds along wavy curtain eruptions, as the scientists' models created simulated images comparable to the real images caught by Cassini.

"Our understanding of Enceladus continues to evolve, and we've come to expect surprises along the way," Linda Spilker of NASA said. "This little ice world is becoming more exciting, not less, as we tease out new details about its subsurface ocean and astonishing geophysical activity."

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