Search Publications
Little or no solar wind enters Venus' atmosphere at solar minimum
Barabash, S.; Russell, C. T.; Lammer, H. +26 more
Venus has no significant internal magnetic field, which allows the solar wind to interact directly with its atmosphere2,3. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Ve…
A dynamic, rotating ring current around Saturn
Krupp, N.; Krimigis, S. M.; Mitchell, D. G. +2 more
The concept of an electrical current encircling the Earth at high altitudes was first proposed in 1917 to explain the depression of the horizontal component of the Earth's magnetic field during geomagnetic storms. In situ measurements of the extent and composition of this current were made some 50years later and an image was obtained in 2001 (ref.…
Venus as a more Earth-like planet
Witasse, Olivier; Taylor, Fredric W.; Svedhem, Håkan +1 more
Venus is Earth's near twin in mass and radius, and our nearest planetary neighbour, yet conditions there are very different in many respects. Its atmosphere, mostly composed of carbon dioxide, has a surface temperature and pressure far higher than those of Earth. Only traces of water are found, although it is likely that there was much more presen…
Hyperion's sponge-like appearance
Burns, J. A.; Denk, T.; Porco, C. +15 more
Hyperion is Saturn's largest known irregularly shaped satellite and the only moon observed to undergo chaotic rotation. Previous work has identified Hyperion's surface as distinct from other small icy objects but left the causes unsettled. Here we report high-resolution images that reveal a unique sponge-like appearance at scales of a few kilometr…
Modulation of Saturn's radio clock by solar wind speed
Lamy, Laurent; Prangé, Renée; Cecconi, Baptiste +2 more
The internal rotation rates of the giant planets can be estimated by cloud motions, but such an approach is not very precise because absolute wind speeds are not known a priori and depend on latitude: periodicities in the radio emissions, thought to be tied to the internal planetary magnetic field, are used instead. Saturn, despite an apparently a…
A belt of moonlets in Saturn's A ring
Schmidt, Jürgen; Sremčević, Miodrag; Albers, Nicole +3 more
The origin and evolution of planetary rings is one of the prominent unsolved problems of planetary sciences, with direct implications for planet-forming processes in pre-planetary disks. The recent detection of four propeller-shaped features in Saturn's A ring proved the presence of large boulder-sized moonlets in the rings. Their existence favour…
Surface composition of Hyperion
Sotin, C.; Brown, R. H.; Baines, K. H. +28 more
Hyperion, Saturn's eighth largest icy satellite, is a body of irregular shape in a state of chaotic rotation. The surface is segregated into two distinct units. A spatially dominant high-albedo unit having the strong signature of H2O ice contrasts with a unit that is about a factor of four lower in albedo and is found mostly in the bott…
An unexpected cooling effect in Saturn's upper atmosphere
Millward, G. H.; Miller, S.; Smith, C. G. A. +2 more
The upper atmospheres of the four Solar System giant planets exhibit high temperatures that cannot be explained by the absorption of sunlight. In the case of Saturn the temperatures predicted by models of solar heating are ~200K, compared to temperatures of ~400K observed independently in the polar regions and at 30° latitude. This unexplained `en…
Tethys and Dione as sources of outward-flowing plasma in Saturn's magnetosphere
André, N.; Coates, A. J.; Dougherty, M. K. +4 more
Rotating at over twice the angular speed of Earth, Saturn imposes a rapid spin on its magnetosphere. As a result, cold, dense plasma is believed to be flung outward from the inner magnetosphere by centrifugal force and replaced by hotter, more tenuous plasma from the outer magnetosphere. The centrifugal interchange of plasmas in rotating magnetosp…
Planetary science: Inside Enceladus
Spencer, John; Grinspoon, David
Chemical analysis of a plume emanating from near the south pole of Enceladus indicates that the interior of this saturnian moon is hot. Could it have been hot enough for complex organic molecules to be made?