Search Publications
The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b
Sing, David K.; Ballester, Gilda E.; Herbert, Floyd
About ten per cent of the known extrasolar planets are gas giants that orbit very close to their parent stars. The atmospheres of these `hot Jupiters' are heated by the immense stellar irradiation. In the case of the planet HD 209458b, this energy deposition results in a hydrodynamic state in the upper atmosphere, allowing for sizeable expansion a…
Morphology and dynamics of the upper cloud layer of Venus
Jaumann, R.; Keller, H. U.; Thomas, N. +7 more
Venus is completely covered by a thick cloud layer, of which the upper part is composed of sulphuric acid and some unknown aerosols. The cloud tops are in fast retrograde rotation (super-rotation), but the factors responsible for this super-rotation are unknown. Here we report observations of Venus with the Venus Monitoring Camera on board the Ven…
The structure of Venus' middle atmosphere and ionosphere
Pätzold, M.; Bird, M. K.; Asmar, S. W. +8 more
The atmosphere and ionosphere of Venus have been studied in the past by spacecraft with remote sensing or in situ techniques. These early missions, however, have left us with questions about, for example, the atmospheric structure in the transition region from the upper troposphere to the lower mesosphere (50-90km) and the remarkably variable stru…
South-polar features on Venus similar to those near the north pole
Baines, K. H.; Langevin, Y.; Lopez-Valverde, M. A. +102 more
Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright `dipole' feature surrounded by a cold `collar' at its north pole. The polar dipole is a `double-eye' feature at the centre of a vas…
Lightning on Venus inferred from whistler-mode waves in the ionosphere
Russell, C. T.; Wei, H. Y.; Zhang, T. L. +3 more
The occurrence of lightning in a planetary atmosphere enables chemical processes to take place that would not occur under standard temperatures and pressures. Although much evidence has been reported for lightning on Venus, some searches have been negative and the existence of lightning has remained controversial. A definitive detection would be t…
A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express
Baines, K. H.; Langevin, Y.; Lopez-Valverde, M. A. +101 more
The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and groun…
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…