Event Horizon Telescope The James Webb Space Telescope About Webb's Orbit The James Webb Space Telescope will observe primarily the infrared light from faint and very distant objects. But all objects, including telescopes, also emit infrared light. To avoid swamping the very faint astronomical signals with radiation from the telescope, the telescope and its instruments must be very cold. The L2 orbit is an elliptical orbit about the semi-stable second Lagrange point . In three of the solutions found by Lagrange, the bodies are in line (L1, L2, and L3); in the other two, the bodies are at the points of equilateral triangles (L4 and L5). In the case of Webb, the 3 bodies involved are the Sun, the Earth and the Webb. Other infrared missions have selected an L2 orbit, like WMAP and H2L2. Here are a few graphics that illustrate how far away Webb will be. (Note that these graphics are not to scale.) Astronomy Cast has a podcast on Lagrange points that you may find interesting.
Découverte de trois exoplanètes potentiellement habitables Des astronomes de l'Observatoire européen austral (ESO) ont découvert dans la constellation du Scorpion un système solaire "doté d'une zone habitable bien remplie", avec trois "super-Terres" où les conditions seraient compatibles avec l'existence d'eau liquide. C'est autour de l'étoile Gliese 667C, d'une masse équivalente à un tiers de celle de notre Soleil, que l'équipe a fait cette trouvaille, à l'aide de l'instrument HARPS équipant le télescope de 3,6 mètres de l'ESO au Chili, indique l'organisation dans un communiqué. Le système de trois étoiles auquel appartient Gliese 667C est abondamment étudié par les scientifiques. Non seulement il est dans le voisinage immédiat de notre système solaire (22 années-lumière) mais il est aussi étonnamment similaire. Il représente donc un candidat de choix pour la recherche d'exoplanètes potentiellement habitables. Au total, les astronomes ont donc identifié au moins cinq planètes, deux autres demandant encore à être confirmées.
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SDSS Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe Like photographers assembling a portfolio of best shots, astronomers have assembled a new, improved portrait of mankind's deepest-ever view of the universe. (Credit: NASA; ESA; G. Illingworth, D. Called the eXtreme Deep Field, or XDF, the photo was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field. The Hubble Ultra Deep Field is an image of a small area of space in the constellation Fornax, created using Hubble Space Telescope data from 2003 and 2004. The new full-color XDF image is even more sensitive, and contains about 5,500 galaxies even within its smaller field of view. Magnificent spiral galaxies similar in shape to our Milky Way and the neighboring Andromeda galaxy appear in this image, as do the large, fuzzy red galaxies where the formation of new stars has ceased. Related Link
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