With Saturn shining bright white in the background, the smooth, lighted edge of the moon Enceladus is interrupted by geysers spewing from the south pole in a newly released visible-light picture from NASA's Cassini orbiter.
The picture is among several new shots of Enceladus snapped during a flyby in November 2009. During the visit, Cassini spotted a never-before-seen population of plumes, confirming researchers' predictions that Enceladus's jets of watery particles vary in number and intensity over time.
"With each Cassini flyby, we learn more about [Enceladus's] extreme activity and what makes this strange moon tick," Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.
Image courtesy NASA/JPL/SSI
Enceladus Bursting at the Seams
Plumes large and small burst from the south pole of Saturn's moon Enceladus in a picture taken by NASA's Cassini orbiter and released February 23, 2010.
The image is actually a mosaic of two shots taken as Cassini made a flyby of the moon in November 2009. The picture shows 30 discrete plumes, 20 of which had never been seen before. Also, one plume that had been spotted in previous pictures appears to have decreased in power, Cassini scientists noted.
In addition to spotting new plumes, the November 2009 Cassini flyby of Saturn's moon Enceladus gave scientists the most detailed map to date of heat coming from a fissure on the moon dubbed the Baghdad Sulcus.
The recently released infrared picture (above right) shows much finer details than previous heat maps of the "tiger stripe" features that spawn Enceladus's plumes. For example, the new data show that broad swaths of heat detected in previous maps of Baghdad Sulcus are actually coming from a narrow region of intense heat no more than half a mile (a kilometer) wide.
The picture also shows that the temperature along Baghdad Sulcus reached more than 180 Kelvin (about -140 degrees Fahrenheit, or -95.5 degrees Celsius) during the flyby—relatively warm for the airless moon.
"The fractures are chilly by Earth standards, but they're a cozy oasis compared to the numbing 50 Kelvin [-370 degrees Fahrenheit, or -223 degrees Celsius] of their surroundings," Cassini team member John Spencer said in a statement.
Image courtesy NASA/JPL/SSI
Wrinkled Face of Enceladus
A wide-angle picture of Enceladus's south pole taken during the November 2009 Cassini flyby shows how fractures give the unusual Saturn moon a wrinkled visage.
The darker lines snaking upward through this frame are the "tiger stripes"—the unusually warm, deep fissures that spawn Enceladus's icy plumes. Some scientists think that the fissures might act like vents sitting on top of underground reservoirs of liquid water.
During the November 2009 Enceladus flyby, NASA's Cassini orbiter took some of the most detailed pictures yet of the Saturn moon's deep fissures, dubbed tiger stripes—including this shot of one named Baghdad Sulcus.
In 2006 Cassini scientists had calculated that the tiger stripes are each about 1,600 feet (500 meters) deep, a mile (1.7 kilometers) wide, and flanked on both sides by 300-foot-high (100-meter-high) ridges. Also, infrared maps show that the stripes are unusually warm compared with the rest of the moon's surface.
"The huge amount of heat pouring out of the tiger stripe fractures may be enough to melt the ice underground," Cassini team member John Spencer said in a statement. "Results like this make Enceladus one of the most exciting places we've found in the solar system."