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A new analysis based on data from NASA's Cassini spacecraft finds a causal link between mysterious, periodic signals from Saturn's magnetic field and explosions of hot ionized gas, known as plasma, around the planet.Scientists have found that enormous clouds of plasma periodically bloom around Saturn and move around the planet like an unbalanced load of laundry on spin cycle. The movement of this hot plasma produces a repeating signature "thump" in measurements of Saturn's rotating magnetic environment and helps to illustrate why scientists have had such a difficult time measuring the length of a day on Saturn."This is a breakthrough that may point us to the origin of the mysteriously changing periodicities that cloud the true rotation period of Saturn," said Pontus Brandt, the lead author on the paper and a Cassini team scientist based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "The big question now is why these explosions occur periodically."The data show how plasma injections, electrical currents and Saturn's magnetic field -- phenomena that are invisible to the human eye -- are partners in an intricate choreography. Periodic plasma explosions form islands of pressure that rotate around Saturn. The islands of pressure "inflate" the magnetic field.A new animation showing the linked behavior is available at http://www.nasa.gov/cassini andhttp://saturn.jpl.nasa.gov... Read MoreThis is an artist's concept of the Saturnian plasma sheet based on data from Cassini magnetospheric imaging instrument. Image credit: NASA/JPL/JHUAPL
As spring continues to unfold at Saturn, April showers on the planet's largest moon, Titan, have brought methane rain to its equatorial deserts, as revealed in images captured by NASA's Cassini spacecraft. This is the first time scientists have obtained current evidence of rain soaking Titan's surface at low latitudes.
Extensive rain from large cloud systems, spotted by Cassini's cameras in late 2010, has apparently darkened the surface of the moon. The best explanation is these areas remained wet after methane rainstorms. The observations released today in the journal Science, combined with earlier results in Geophysical Research Letters last month, show the weather systems of Titan's thick atmosphere and the changes wrought on its surface are affected by the changing seasons, notes NASA JPL.
Near the beginning of the movie/animation made from images taken by NASA's Cassini spacecraft above, a particularly large cloud can be seen directly over and east of Titan's huge sea, Kraken Mare. If full, Kraken Mare, at 400,000 square kilometers (154,000 square miles), would be almost five times the size of North America's Lake Superior.
Over the past several years, Cassini has consistently observed clouds at Titan's mid-southern latitudes. More recent images also show clouds close to the moon's equator (see PIA12810). These observations provide evidence of a seasonal shift of Titan's weather systems to low latitudes following the Saturnian system's August 2009 equinox. (During equinox, the sun lies directly over the equator.)
Credit: dark-sky-misteries.blogspot.com
