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Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae
Coates, A. J.; Dougherty, M. K.; Kurth, W. S. +11 more
The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, wh…
In situ multi-satellite detection of coherent vortices as a manifestation of Alfvénic turbulence
Sundkvist, David; Vaivads, Andris; Krasnoselskikh, Vladimir +4 more
Turbulence in fluids and plasmas is a ubiquitous phenomenon driven by a variety of sources-currents, sheared flows, gradients in density and temperature, and so on. Turbulence involves fluctuations of physical properties on many different scales, which interact nonlinearly to produce self-organized structures in the form of vortices. Vortex motion…
A soft solid surface on Titan as revealed by the Huygens Surface Science Package
Banaszkiewicz, Marek; Zarnecki, John C.; Lorenz, Ralph D. +23 more
The surface of Saturn's largest satellite-Titan-is largely obscured by an optically thick atmospheric haze, and so its nature has been the subject of considerable speculation and discussion. The Huygens probe entered Titan's atmosphere on 14 January 2005 and descended to the surface using a parachute system. Here we report measurements made just a…
Saturn's moon Phoebe as a captured body from the outer Solar System
Lunine, Jonathan I.; Johnson, Torrence V.
The orbital properties of Phoebe, one of Saturn's irregular moons, suggest that it was captured by the ringed planet's gravitational field rather than formed in situ. Phoebe's generally dark surface shows evidence of water ice, but otherwise the surface most closely resembles that of C-type asteroids and small outer Solar System bodies such as Chi…
An Earth-like correspondence between Saturn's auroral features and radio emission
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +12 more
Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae, and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dyna…
Discovery of a flank caldera and very young glacial activity at Hecates Tholus, Mars
HRSC Co-Investigator Team; Head, James W.; Greeley, Ronald +8 more
The majority of volcanic products on Mars are thought to be mafic and effusive. Explosive eruptions of basic to ultrabasic chemistry are expected to be common, but evidence for them is rare and mostly confined to very old surface features. Here we present new image and topographic data from the High Resolution Stereo Camera that reveal previously …
Discovery of a bright quasar without a massive host galaxy
Wisotzki, Lutz; Jablonka, Pascale; Courbin, Frédéric +4 more
A quasar is thought to be powered by the infall of matter onto a supermassive black hole at the centre of a massive galaxy. Because the optical luminosity of quasars exceeds that of their host galaxy, disentangling the two components can be difficult. This led in the 1990s to the controversial claim of the discovery of `naked' quasars. Since then,…
High-velocity streams of dust originating from Saturn
Grün, Eberhard; Kempf, Sascha; Srama, Ralf +5 more
High-velocity submicrometre-sized dust particles expelled from the jovian system have been identified by dust detectors on board several spacecraft. On the basis of periodicities in the dust impact rate, Jupiter's moon Io was found to be the dominant source of the streams. The grains become positively charged within the plasma environment of Jupit…
No oceans on Titan from the absence of a near-infrared specular reflection
West, R. A.; Brown, M. E.; Roe, H. G. +2 more
With its substantial atmosphere of nitrogen, hydrocarbons and nitriles, Saturn's moon Titan is a unique planetary satellite. Photochemical processing of the gaseous constituents produces an extended haze that obscures the surface. Soon after the Voyager fly-bys in 1980 and 1981 photochemical models led to the conclusion that there should be enough…
How Prometheus creates structure in Saturn's F ring
Porco, Carolyn C.; Burns, Joseph A.; Murray, Carl D. +4 more
Images of Saturn's narrow and contorted F ring returned by the Cassini spacecraft have revealed phenomena not previously detected in any planetary ring system. The perturbing effect of the inner shepherding satellite, Prometheus, seems to introduce channels through the F ring and a `streamer'-a line of particles that link the ring to the satellite…