Saturn’s radio emissions and bright auroras are linked

Just as the static on an AM radio grows louder with the approach of a summer lightning storm, strong radio emissions accompany bright auroral spots -- similar to Earth’s northern lights -- on the planet Saturn, according to a research paper published in the Thursday, Feb. 17 issue of the journal Nature.

The Cassini spacecraft is the first to explore the Saturn system of rings and moons from orbit. Cassini entered orbit on Jun. 30, 2004 and immediately began sending back intriguing images and data. According to William Kurth, research scientist in the University of Iowa College of Liberal Arts and Sciences Department of Physics and Astronomy, the data collected in early 2004, indicated that Saturn’s strong radio emissions grow stronger when the solar wind blows harder.

"We had expected that this might be the case, based on our understanding of auroral radio signals from Earth’s auroras, but this is the first time we’ve been able to compare Saturn’s radio emissions with detailed images of the aurora," Kurth says. "This is important to our on-going Cassini studies because this association allows us to have some idea of what the aurora are doing throughout the mission from our continuous radio observations."

Co-author Don Gurnett, Cassini Radio and Plasma Wave Science (RPWS) instrument principal investigator, says the finding means that radio emissions from Saturn’s aurora are very similar to radio emissions from the Earth’s aurora.

Kurth says that one of Cassini’s objectives is to understand how the magnetic field around Saturn, called its magnetosphere, responds to the influence of the solar wind, a hot gas composed of electrons and ions that originates at the Sun and blows past the planets at speeds around one million miles per hour.

Two related papers published by other researchers in Thursday’s issue of Nature show that, like a flaming log in a campfire, Saturn’s aurora become brighter and more expansive when the solar wind blows harder. However, the distribution of auroras on Saturn differs from those on Earth.

Other discoveries made by UI researchers using the RPWS instrument have included finding that lightning on Saturn is roughly one million times stronger than lightning on Earth; observing that Cassini impacted dust particles as it traversed Saturn’s rings; and learning that Saturn’s radio rotation rate varies.

The radio sounds of Saturn’s rotation -- resembling a heartbeat -- and other sounds of space can be heard by visiting http://www-pw.physics.uiowa.edu/space-audio .

Related stories:

Cassini Images Bizarre Hexagon on Saturn
An odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn has captured the interest of scientists with NASA's Cassini mission.
The antenna bride and bridegroom
The Atacama Large Millimeter/submillimeter Array (ALMA), an international telescope project, reached a major milestone on 2 March, when two 12-m ALMA prototype antennas were first linked together as an integrated system to observe an astronomical object.
Cassini cameras spot powerful new lightning storm on Saturn
Following the recent detection of Saturnian radio bursts by NASA's Cassini spacecraft that indicated a rare and powerful atmospheric storm, Cassini imaging scientists have spotted the storm in an unlikely fashion: they looked for it in the dark.
Space Physicist finds 'lumpy' ionosphere, glimpses of the subsurface of Mars
University of Iowa Space Physicist Don Gurnett and his UI colleagues report that a scientific instrument aboard the European Space Agency's (ESA) Mars Express spacecraft is working perfectly and that its data have so far revealed that Mars' ionosphere -- part of the upper atmosphere -- is very lumpy and complex, and that the instrument can "see" hidden craters and thick layers of ice beneath the planet's surface.
Cassini Reveals Saturn's Eerie-Sounding Radio Emissions
Saturn's radio emissions could be mistaken for a Halloween sound track.
That's how two researchers describe their recent findings, published in the July 23 issue of the Geophysical Research Letters. Their paper is based on data from the Cassini spacecraft radio and plasma wave science instrument. The study investigates sounds that are not just eerie, but also descriptive of a phenomenon similar to Earth's northern lights.
RHESSI satellite captures giant gamma-ray flare
Astronomers around the world recorded late last year the brightest explosion ever of high-energy X-rays and gamma rays - a split-second flash from the other side of our galaxy that was strong enough to affect the Earth's atmosphere.
The flash, called a soft gamma repeater flare, reached Earth on Dec. 27 and was detected by at least 15 satellites and spacecraft between Earth and Saturn, swamping most of their detectors. Some of the best observations were recorded by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), a NASA/University of California, Berkeley, satellite launched in 2002 to study gamma-ray emissions from solar flares.
Saturn’s aurora – not as we thought! Comment from UK scientists
Results which combine data from the joint NASA/ESA/ASI Cassini Huygens space mission and the Hubble Space Telescope, published in Nature today (17th February 2005), reveal that Saturn’s auroras, long thought to be a cross between those of Earth and Jupiter, are in fact different and may even be unique to Saturn.

Saturn's Aurora Defy Scientists' Expectations
Aurora on Saturn behave in ways different from how scientists have thought possible for the last 25 years, according to new research by a team of astronomers led by John Clarke, a professor in BU’s Department of Astronomy and in the department’s Center for Space Physics. The team’s findings have overturned theories about how Saturn’s magnetosphere behaves and how its aurora are generated. Their results will be published in the February 17 issue of Nature.

News discussion:

Space & Earth science news