Photo de la semaine

23 avril 2012: Stéphane Guisard, ambassadeur photo de l'ESO, a immortalisé ce panorama étonnant depuis le site d'ALMA, l'Atacama Large Millimeter/submillimeter Array, dans les Andes chiliennes. Le plateau de Chajnantor, haut de 5000 mètres et extrêmement sec, offre l'endroit idéal pour ce télescope à la pointe de la technologie, qui étudie l'Univers en lumière millimétrique et submillimétrique.De nombreuses antennes géantes dominent le centre de l'image. Lorsque ALMA sera terminé, il comptera 54 de ces antennes de 12 mètres de diamètre. Au-dessus du réseau, l'arc de la Voie lactée sert de toile de fond resplendissante. Lorsque le panorama a été pris, la Lune se trouvait près du centre de la Voie lactée dans le ciel, sa lumière baignant les antennes d'une étrange lueur nocturne. Le Grand et le Petit Nuage de Magellan, les plus grandes galaxies naines satellites de la Voie lactée, apparaissent comme deux taches lumineuses dans le ciel à gauche. Une traînée ...

16 avril 2012: L'Atacama Pathfinder Experiment (APEX) télescope regarde vers le ciel durant une brillante nuit éclairée par la Lune sur Chajnantor, l'un des plus haut et plus sec site d'observatoire du monde. Des trésors astronomiques remplissent le ciel au-dessus du télescope, une preuve des excellentes conditions offertes par ce site dans la région d'Atacama au Chili. Sur le côté gauche brille une étoile qui forme la queue de la constellation du Scorpion. L'aiguillon du Scorpion est représentée par deux étoiles brillantes particulièrement proche l'une de l'autre. Traversant le ciel et ressemblant à une bande de faibles nuages lumineux est le plan de la Voie Lactée. Entre le Scorpion et la prochaine constellation vers la droite, le Sagittaire, qui se trouve au-dessus de l'antenne d'APEX, un amas d'étoiles étincelantes peut être clairement vu. C'est l'amas ouvert de Messier 7, connu comme l'amas de Ptolémée. En-dessous de Messier 7 et un peu à droite ...

9 avril 2012: Although Cerro Chico reaches the remarkable altitude of 5300 metres above sea level, it is only a small mountain in the majestic landscape of the Andean plateaux. Indeed, its own name means simply “small mountain” in Spanish. However, due to its position on the plateau of Chajnantor, the top of Cerro Chico offers an excellent and relatively easy-to-reach vantage point from which to enjoy this stunning view. This 360 degree panorama picture is centred on the northeast, where the highest volcanoes — most of them above 5500 metres — are seen. In the centre is Cerro Chajnantor itself. To the right, on the plateau, is the Atacama Pathfinder Experiment (APEX) telescope with Cerro Chascon behind it. Further to the right, to the southeast, the Chajnantor plateau is almost fully visible. In addition to the APEX telescope, three Atacama Large Millimeter/submillimeter Array (ALMA) antennas can be seen, on the right. Many ...

2 avril 2012: ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany. This historical image was taken around 1970 from the La Silla dormitories, located lower on the mountain than the telescope domes. The photo looks up towards the highest point of the mountain, on the left. The metallic structure visible near the top of this peak is not a telescope, but a water tank for the site. The white dome in the centre of the image is that of the ESO 1-metre Schmidt telescope, which started work in February 1972. On the far right of the ...

26 mars 2012: French photographer Serge Brunier — one of ESO’s Photo Ambassadors — has created this seamless 360-degree panorama of the Chajnantor plateau in the Atacama Desert, where the Atacama Large Millimeter/submillimeter Array (ALMA) is under construction. The panorama projection has slightly warped the shapes of the ALMA antennas, but it still gives a sense of what it would be like to stand in the middle of this impressive new observatory. The 360 degree panorama view also demonstrates the complete isolation of the Chajnantor plateau; at an altitude of 5000 metres, the backdrop is almost featureless, except for a few mountain peaks and hilltops. Although constructing such an ambitious telescope project in a remote and harsh environment is challenging, the high altitude location is perfect for submillimetre astronomy. That’s because water vapour in the atmosphere absorbs this type of radiation, but the air is much drier at high altitude sites such as ...

19 mars 2012: The Very Large Telescope has captured another member of the Leo I group of galaxies, in the constellation of Leo (The Lion). The galaxy Messier 95 stands boldly face-on, offering an ideal view of its spiral structure. The spiral arms form an almost perfect circle around the galactic centre before they spread out, creating a mane-like effect of which any lion would be proud. Another, perhaps even more striking, feature of Messier 95 is its blazing golden core. It contains a nuclear star-forming ring, almost 2000 light-years across, where a large proportion of the galaxy’s star formation takes place. This phenomenon occurs mostly in barred spiral galaxies such as Messier 95 and our home, the Milky Way. In the Leo I group, Messier 95 is outshone by its brother Messier 96 (see potw1143). Messier 96 is in fact the brightest member of the group and — as “leader of the ...

12 mars 2012: The domes of ESO’s Very Large Telescope sit atop Cerro Paranal, basking in the sunlight of another glorious cloudless day. But something is different about this picture: a fine layer of snow has settled across the desert landscape. This isn’t something you see every day: quite the opposite in fact, as the Atacama Desert gets almost no precipitation. Several factors contribute to the dry conditions in the Atacama. The Andes mountain range blocks rain from the east, and the Chilean Coast Range from the west. The cold offshore Humboldt current in the Pacific Ocean creates a coastal inversion layer of cool air, which prevents rain clouds from developing. A region of high pressure in the south-eastern Pacific Ocean creates circulating winds, forming an anticyclone, which also helps to keep the climate of the Atacama dry. Thanks to all these factors, the region is widely regarded as the driest place on ...

5 mars 2012: L'ESO a cinquante ans cette année, pour célébrer cet anniversaire important nous allons vous montrer des morceaux de notre histoire. Une fois par mois durant 2012, une Photo de la Semaine comparant le Passé et le Présent montrera comment les choses ont changé durant les décennies au observatoires de La Silla et de Paranal, les installations ESO à Santiago du Chili et le Siège Social à Garching / Munich, Allemagne. Voici deux photos de La Silla, prises en Juin 1968 et de nos jours à partir des réservoirs d'eau, regardant le reste du site. On peut examiner les changements avec cette comparaison d'images. Dans l'image historique, le quartier résidentiel provisoire est visible dans l'avant-plan. Les trois télescopes dans l'arrière-plan sont, de gauche à droite, le Grand Prism Objectif (GPO, première observation en 1968), le télescope ESO de 1 mètre (1966) et le teélescope ESO de 1.5 mètres (1968). Ces trois ...

27 février 2012: The dynamism of ESO's Very Large Telescope in operation is wonderfully encapsulated in this unusual photograph, taken just after sunset at the moment Unit Telescope 1 starts work. An extended exposure time of 26 seconds has allowed ESO Photo Ambassador Gerhard Hüdepohl to record the movement of the dome, looking out through the opening from within, as the system swings into action. The rotating walls of the dome look like an ethereal swirl through which a slice of the Atacama Desert can be glimpsed, while the crisp dusk sky provides a splash of cool blue. The telescope structure, seen stationary in the centre of the image, houses a mirror 8.2 metres in diameter, designed to collect light from the far reaches of our Universe. The dome itself is also an engineering marvel, moving with extreme precision and allowing for careful temperature control lest warm air currents disrupt observations. Links ESO ...

20 février 2012: ESO’s Paranal Observatory facilities, such as the Residencia, give people who work at the site a welcome shelter from the surrounding inhospitable environment. In spite of that, they also offer interesting options for those who wish to enjoy the stark and silent beauty of the Atacama Desert. See this stunning panorama! Among these is the Star Track, a walking path which connects the Residencia with the Very Large Telescope (VLT) platform, on the 2600-metre summit of Cerro Paranal. Built in 2001, the Star Track covers about two kilometres in distance and a difference in height of 200 metres. The last part of the track snakes around the west side of the mountain, offering incomparable views. This 360 degree panoramic picture is centred facing north, so the right and left edges of the picture correspond to the south. To the north, the VLT control room and part of one of the ...

13 février 2012: There is a lot to love about astronomy, and — in time for Valentine's Day — photographer Julien Girard offers a "heartfelt” example in this image. A bright pink symbol of love appears to float ethereally against the backdrop of the night sky over ESO's Paranal Observatory in northern Chile. Girard drew the heart in the air by shining a tiny flashlight keychain at the camera during a 25-second exposure with a tripod. The central region of the Milky Way appears in the middle of the heart, as the plane of our galaxy stretches across the image. The stars of the constellation of Corona Australis (The Southern Crown) form a glittering arc of jewels at the top of the heart's left lobe. The diffuse glow to the left of the heart's lowest point is zodiacal light, caused by the scattering of light from the Sun by dust particles in the ...

6 février 2012: L'ESO a cinquante ans cette année, pour célébrer cet anniversaire important nous allons vous montrer des morceaux de notre histoire. Une fois par mois durant 2012, une Photo de la Semaine comparant le Passé et le Présent montrera comment les choses ont changé durant les décennies au observatoires de La Silla et de Paranal, les installations ESO à Santiago du Chili et le Siège Social à Garching / Munich, Allemagne. Ces deux photos montrent l'observatoire de La Silla en 1960 et de nos jours. On peut examiner les différence entre les deux photos avec cette comparaison. Les télescopes sont les seuls choses qui ont changé, les voitures dans les photos montrent également le temps qui s'est écoulé. La Volkswagen 1 Variant dans la première image a été remplacée dans la seconde image par une Suzuki 4WD. De nos jours, tout les véhicules ESO à La Silla sont blancs pour ameliorer ...

30 janvier 2012: In this photograph, taken by ESO Photo Ambassador Gianluca Lombardi, the Sun is rising and bathing the Chilean Atacama Desert in a familiar soft reddish glow. But this image, from 13 July 2011, has also captured something out of the ordinary: a dark shadow lurking on the horizon. Gianluca took this photograph from Cerro Armazones, looking west. Armazones is the future home of the world’s biggest eye on the sky: the upcoming European Extremely Large Telescope (E-ELT). The Sun rose behind Gianluca in just the right place to cast a daunting shadow of the 3046-metre-high mountain onto the Earth’s atmosphere in the distance. The shadow can be seen reaching over the vast desert landscape, and up across the horizon on the left side of the image. The bright summit visible on the right of the image is Cerro Paranal, at an altitude of 2600 metres. It is only 20 kilometres ...

23 janvier 2012: This image shows the swirling shape of galaxy NGC 2217, in the constellation of Canis Major (The Great Dog). In the central region of the galaxy is a distinctive bar of stars within an oval ring. Further out, a set of tightly wound spiral arms almost form a circular ring around the galaxy. NGC 2217 is therefore classified as a barred spiral galaxy, and its circular appearance indicates that we see it nearly face-on. The outer spiral arms have a bluish colour, indicating the presence of hot, luminous, young stars, born out of clouds of interstellar gas. The central bulge and bar are yellower in appearance, due to the presence of older stars. Dark streaks can also be seen in places against the galaxy’s arms and central bulge, where lanes of cosmic dust block out some of the starlight. The majority of spiral galaxies in the local Universe — including ...

16 janvier 2012: Workers on the Atacama Large Millimeter/submillimeter Array (ALMA) project stand next to three of the telescope’s antennas. This photograph gives a real sense of the scale of the giant dishes, whose 12-metre diameters are about seven times the average human height. When completed, ALMA will consist of 66 high-precision antennas, 54 of them with 12-metre dishes as seen in this image, and 12 more compact ones with diameters of 7 metres. The yellow 28-wheel transporter vehicle, which has to be powerful enough to carry the 100-tonne antennas, is built on a similarly giant scale. This photograph was taken at the 2900-metre-high ALMA Operations Support Facility in the foothills of the Chilean Andes, where the antennas are assembled and tested. On the left is one of the European ALMA antennas, pointing at the horizon. Behind it is one of the antennas provided to the project by Japan, while on the right, ...

9 janvier 2012: The picture is part of the COMBO-17 survey (Classifying Objects by Medium-Band Observations in 17 Filters), a project dedicated to recording detailed images of small patches of the sky through filters of 17 different colours. The area covered in this image is only about the size of the full Moon, but thousands of galaxies can be identified just within this small region. The image was taken with an exposure time of almost seven hours, which allowed the camera to capture the light from very faint and distant objects, as well as those that are closer to us. Galaxies with clear and regular structures, such as the spiral specimen viewed edge-on near the upper left corner, are only up to a few billion light-years away. The fainter, fuzzier objects are so far away that it has taken nine or ten billion years for their light to reach us. The COMBO-17 survey ...

3 janvier 2012: ESO turns 50 this year, and to celebrate this important anniversary, we will be showing you glimpses into our history. Once a month throughout 2012, a special “then and now” comparison Picture of the Week will show how things have changed over the decades at the La Silla and Paranal observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany. Our first stop on this journey through time is at La Silla, the first of ESO’s observatory sites. The historical image was taken in the late 1960s or early 1970s from the dome of the ESO 1.52-metre telescope, which had its first light in 1968. A second photograph, taken in the present day, shows how much the observatory has changed over the decades. You can examine the changes with our mouseover image comparison. In the historical image, we can see the ESO 1-metre telescope ...

26 décembre 2011: As night was falling over ESO’s La Silla Observatory in Chile on 20 December 2009, the sky was not yet dark enough for the telescopes to start observations. But conditions were perfect to perform a clever trick with the dome of the Swiss 1.2-metre Leonhard Euler Telescope: allowing us to peer inside with this photograph apparently taken through the dome. This image is a 75-second exposure taken while the slit of the Euler telescope’s dome was performing half a rotation at full speed. Through the ghostly blur of the moving dome walls, the telescope is clearly visible. A dim light was switched on in the interior of the building especially for the purpose of this photo. The picture was taken by Malte Tewes, a young astronomer from the École Polytechnique Fédérale de Lausanne in Switzerland, who had just finished a two-week observing run at the telescope on the evening in ...

19 décembre 2011: Bathed in the pristine light of the Chilean Atacama Desert, the ESO VLT’s Auxiliary Telescope 2 stands on Cerro Paranal. It is one of four that are used with the Very Large Telescope Interferometer. During the day, its bulbous dome is closed, protecting the sensitive telescope within. The magnificent 6739-metre volcano Llullaillaco stands proudly in the background of this photograph. Although it looks relatively close on the horizon, it is actually an incredible 190 kilometres away, on the border with Argentina. That Llullaillaco can be seen so clearly is evidence of the region’s unparallelled atmospheric conditions. The clear air is one of the many factors that make this such a wonderful location for astronomical observatories. It is from this excellent vantage point that ESO astronomers study objects that are not just hundreds of kilometres in the distance, but billions of light-years away. This photograph was taken by ESO Photo Ambassador ...

12 décembre 2011: Cette vue panoramique du plateau Chajnantor, faisant environ 180 degrés allant du Nord (Gauche) vers le Sud (Droite) montre les antennes de l'Atacama Large Millimeter/submillimeter Array (ALMA) dans un paysage surnaturel. Des objets célestes familiers peuvent être vus dans le ciel nocturne derrière les antennes. Ce ciel nocturne clair comme de l'eau de roche explique pourquoi le Chili est la demeure de non seulement l'ALMA mais également de plusieurs autres observatoires astronomiques. Cette image est juste une partie d'un panorama encore plus grand de Chajnantor. À l'avant-plan, les antennes d'ALMA de 12 mètres de diamètre sont en pleine action, travaillant en tant qu'un télescope géant, durant les premières phases d'observations scientifiques de l'observatoire. Tout à gauche, un amas de plus petites antennes de 7 mètres sont illuminés. Le croissant de Lune, quoique pas visible sur l'image, émet des ombres obscures sur les antennes. Dans le ciel au-dessus des antennes, "l'étoile" ...