Hampatura: janvier 2007

dimanche 21 janvier 2007

Sombrero galaxy

The Sombrero Galaxy in Infrared
Credit: R. Kennicutt (Steward Obs.) et al., SSC, JPL, Caltech, NASA

This floating ring is the size of a galaxy. In fact, it is part of the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light. The above image shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away. M104 can be seen with a small telescope in the direction of the constellation Virgo.

jeudi 4 janvier 2007

Mars

This false-color subframe of an image from the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter shows the north polar layered deposits at top and darker materials at bottom, exposed in a scarp at the head of Chasma Boreale, a large canyon eroded into the layered deposits.

The polar layered deposits appear red because of dust mixed within them, but are ice-rich as indicated by previous observations. Water ice in the layered deposits is probably responsible for the pattern of fractures seen near the top of the scarp. The darker material below the layered deposits may have been deposited as sand dunes, as indicated by the crossbedding (truncation of curved lines) seen near the middle of the scarp. It appears that brighter, ice-rich layers were deposited between the dark dunes in places. Exposures such as these are useful in understanding recent climate variations that are likely recorded in the polar layered deposits.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

Image credit: NASA/JPL-Caltech/Univ. of Arizona.

Dans notre île, il n'y avait ni arbres ni buissons. Elle avait l'air d'une chaîne de montagnes tombée en ruines, et tout autour, les écueils râlaient dans le ressac. Mais nuit et jour il tonnait, écoute ! C'était la mer. Il ventait ; le vent criait continuellement, et quand un humain passait sur la lande, il ondoyait comme un drapeau en loques. A toute heure du jour et de la nuit, les mouettes stridaient. L'île et la mer leur appartenaient. Parfois l'île s'abîmait littéralement sous leur déchirant bruit de limes. Quand je nageais là-bas près des récifs, elles tendaient leurs têtes blanches, inquiètes ; il y en avait trois, cinq, dix, mais dès que j'approchais, il y en avait des centaines, des milliers. Elles tournoyaient en stridant, m'enveloppant domme un nuage grondant d'orage, et j'étais saisi d'une terreur mystérieuse, tant leur nombre était grand. Et souvent encore elles crient dans mes rêves.

Bernhard Kellermann La mer