Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Moon”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed2005

Compositional maps of Saturn's moon Phoebe from imaging spectroscopy.

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, circular orbits) probably accreted within the sub-nebula in which Saturn itself formed. Here we report imaging spectroscopy of Phoebe resulting from the Cassini-Huygens spacecraft encounter on 11 June 2004. We mapped ferrous-iron-bearing minerals, bound water, trapped CO2, probable phyllosilicates, organics, nitriles and cyanide compounds. Detection of these compounds on Phoebe makes it one of the most compositionally diverse objects yet observed in our Solar System. It is likely that Phoebe's surface contains primitive materials from the outer Solar System, indicating a surface of cometary origin.

Journal Article↗
PubMed2006

Neptune's capture of its moon Triton in a binary-planet gravitational encounter.

Triton is Neptune's principal satellite and is by far the largest retrograde satellite in the Solar System (its mass is approximately 40 per cent greater than that of Pluto). Its inclined and circular orbit lies between a group of small inner prograde satellites and a number of exterior irregular satellites with both prograde and retrograde orbits. This unusual configuration has led to the belief that Triton originally orbited the Sun before being captured in orbit around Neptune. Existing models for its capture, however, all have significant bottlenecks that make their effectiveness doubtful. Here we report that a three-body gravitational encounter between a binary system (of approximately 10(3)-kilometre-sized bodies) and Neptune is a far more likely explanation for Triton's capture. Our model predicts that Triton was once a member of a binary with a range of plausible characteristics, including ones similar to the Pluto-Charon pair.

Journal Article↗
PubMed2006

Diapir-induced reorientation of Saturn's moon Enceladus.

Enceladus is a small icy satellite of Saturn. Its south polar region consists of young, tectonically deformed terrain and has an anomalously high heat flux. This heat flux is probably due to localized tidal dissipation within either the ice shell or the underlying silicate core. The surface deformation is plausibly due to upwelling of low-density material (diapirism) as a result of this tidal heating. Here we show that the current polar location of the hotspot can be explained by reorientation of the satellite's rotation axis because of the presence of a low-density diapir. If the diapir is in the ice shell, then the shell must be relatively thick and maintain significant rigidity (elastic thickness greater than approximately 0.5 km); if the diapir is in the silicate core, then Enceladus cannot possess a global subsurface ocean, because the core must be coupled to the overlying ice for reorientation to occur. The reorientation generates large (approximately 10 MPa) tectonic stress patterns that are compatible with the observed deformation of the south polar region. We predict that the distribution of impact craters on the surface will not show the usual leading hemisphere-trailing hemisphere asymmetry. A low-density diapir also yields a potentially observable negative gravity anomaly.

Journal Article↗
PubMed2006

Methane storms on Saturn's moon Titan.

The presence of dry fluvial river channels and the intense cloud activity in the south pole of Titan over the past few years suggest the presence of methane rain. The nitrogen atmosphere of Titan therefore appears to support a methane meteorological cycle that sculptures the surface and controls its properties. Titan and Earth are the only worlds in the Solar System where rain reaches the surface, although the atmospheric cycles of water and methane are expected to be very different. Here we report three-dimensional dynamical calculations showing that severe methane convective storms accompanied by intense precipitation may occur in Titan under the right environmental conditions. The strongest storms grow when the methane relative humidity in the middle troposphere is above 80 per cent, producing updrafts with maximum velocities of 20 m s(-1), able to reach altitudes of 30 km before dissipating in 5-8 h. Raindrops of 1-5 mm in radius produce precipitation rainfalls on the surface as high as 110 kg m(-2) and are comparable to flash flood events on Earth.

Journal Article↗
PubMed2003

The new moon.

Explore the source record for details and available documents.

Journal Article↗
PubMed2003

[Xeroderma pigmentosum: children of the moon].

Xeroderma pigmentosum is based on a genetic defect in the DNA repair system, which is diagnosed in early childhood. Xeroderma pigmentosum is a rare disorder, which is transmitted in an autosomal recessive manner. Children with xeroderma pigmentosum display hypersensitivity to ultraviolet (UV) radiation. These patients experience serious sunburns with minimal exposure and then develop poikiloderma in the sun-exposed areas. Squamous cell carcinomas, basal cell carcinomas and malignant melanomas all appear during childhood. The majority of patients do not reach adult, but die from metastatic cutaneous malignancies. Genetically, xeroderma pigmentosum is differentiated into 7 complementation groups (XP-A to XP-G) and the xeroderma pigmentosum variants (XP-V). The assignment to the specific complementation group is made by fusing of xeroderma pigmentosum fibroblasts. Xeroderma pigmentosum must be distinguished from other so-called DNA repair deficiency syndromes, including Cockayne syndrome and trichothiodystrophy. A topical DNA repair enzyme appears to be helpful. A recombinant liposomal encapsulated T4 endonuclease V repairs UV-induced cyclobutane-pyrimidine dimers. Direct curative treatment of xeroderma pigmentosum could be achieved with gene therapy in future. Transfection of an intact repair gene which specifically codes for the missing repair protein could open new possibilities in the therapy of xeroderma pigmentosum.

Child↗