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Differentiation of the asteroid Ceres as revealed by its shape
Russell, C. T.; Stern, S. A.; Young, E. F. +4 more
The accretion of bodies in the asteroid belt was halted nearly 4.6billion years ago by the gravitational influence of the newly formed giant planet Jupiter. The asteroid belt therefore preserves a record of both this earliest epoch of Solar System formation and variation of conditions within the solar nebula. Spectral features in reflected sunligh…
The mass of the missing baryons in the X-ray forest of the warm-hot intergalactic medium
Elvis, Martin; Zezas, Andreas; Marshall, Herman +7 more
Recent cosmological measurements indicate that baryons comprise about four per cent of the total mass-energy density of the Universe, which is in accord with the predictions arising from studies of the production of the lightest elements. It is also in agreement with the actual number of baryons detected at early times (redshifts z > 2). Close …
Release of volatiles from a possible cryovolcano from near-infrared imaging of Titan
Rodriguez, S.; Sotin, C.; Brown, R. H. +23 more
Titan is the only satellite in our Solar System with a dense atmosphere. The surface pressure is 1.5bar (ref. 1) and, similar to the Earth, N2 is the main component of the atmosphere. Methane is the second most important component, but it is photodissociated on a timescale of 107years (ref. 3). This short timescale has led to…
Discovery of an aurora on Mars
Bertaux, Jean-Loup; Leblanc, François; Korablev, Oleg +5 more
In the high-latitude regions of Earth, aurorae are the often-spectacular visual manifestation of the interaction between electrically charged particles (electrons, protons or ions) with the neutral upper atmosphere, as they precipitate along magnetic field lines. More generally, auroral emissions in planetary atmospheres ``are those that result fr…
Complex organic matter in Titan's atmospheric aerosols from in situ pyrolysis and analysis
Steller, M.; Atreya, S. K.; Owen, T. +19 more
Aerosols in Titan's atmosphere play an important role in determining its thermal structure. They also serve as sinks for organic vapours and can act as condensation nuclei for the formation of clouds, where the condensation efficiency will depend on the chemical composition of the aerosols. So far, however, no direct information has been available…
An overview of the descent and landing of the Huygens probe on Titan
Lebreton, Jean-Pierre; Witasse, Olivier; Matson, Dennis L. +9 more
Titan, Saturn's largest moon, is the only Solar System planetary body other than Earth with a thick nitrogen atmosphere. The Voyager spacecraft confirmed that methane was the second-most abundant atmospheric constituent in Titan's atmosphere, and revealed a rich organic chemistry, but its cameras could not see through the thick organic haze. After…
Compositional maps of Saturn's moon Phoebe from imaging spectroscopy
Sotin, C.; Baines, K. H.; Nicholson, P. D. +23 more
The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, ci…
Evidence from the Mars Express High Resolution Stereo Camera for a frozen sea close to Mars' equator
HRSC Co-Investigator Team; Head, James W.; van Gasselt, Stephan +10 more
It is thought that the Cerberus Fossae fissures on Mars were the source of both lava and water floods two to ten million years ago. Evidence for the resulting lava plains has been identified in eastern Elysium, but seas and lakes from these fissures and previous water flooding events were presumed to have evaporated and sublimed away. Here we pres…
The vertical profile of winds on Titan
Plettemeier, D.; Gurvits, L. I.; Pogrebenko, S. V. +12 more
One of Titan's most intriguing attributes is its copious but featureless atmosphere. The Voyager 1 fly-by and occultation in 1980 provided the first radial survey of Titan's atmospheric pressure and temperature and evidence for the presence of strong zonal winds. It was realized that the motion of an atmospheric probe could be used to study the wi…
Morphological differences between Saturn's ultraviolet aurorae and those of Earth and Jupiter
Kim, J.; Hill, T.; Crary, F. +10 more
It has often been stated that Saturn's magnetosphere and aurorae are intermediate between those of Earth, where the dominant processes are solar wind driven, and those of Jupiter, where processes are driven by a large source of internal plasma. But this view is based on information about Saturn that is far inferior to what is now available. Here w…