Picture of the Week

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potw1215 — Picture of the Week
All Around Chajnantor — A 360-degree panorama
9 April 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 ...
potw1214 — Picture of the Week
La Silla, the First Home for ESO’s Telescopes — ESO’s first observatory site Then and Now
2 April 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 ...
potw1213 — Picture of the Week
Wish You Were Here?
26 March 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 ...
potw1212 — Picture of the Week
The VLT goes lion hunting
19 March 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 ...
potw1211 — Picture of the Week
A Dusting of Snow in the Atacama Desert
12 March 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 ...
potw1210 — Picture of the Week
A Window to the Past — La Silla’s transformation through time
5 March 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. Here are two photographs of La Silla, taken in June 1968 and the present day from near the observatory’s water tanks, looking over the rest of the site. You can examine the changes with our mouseover image comparison. In the historical image, the provisional residential area is visible in the foreground. The three telescopes in the background are, from left to right, the Grand Prism Objectif (GPO, first light in 1968), the ESO 1-metre telescope (first light in 1966), and the ESO 1.5-metre telescope (first ...
potw1209 — Picture of the Week
Spinning into Action
27 February 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 ...
potw1208 — Picture of the Week
Boldly going up Cerro Paranal
20 February 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 ...
potw1207 — Picture of the Week
The Heart of the Milky Way, for Valentine’s Day
13 February 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 ...
potw1206 — Picture of the Week
A Drive Through Time — How telescopes, and cars, have changed at La Silla
6 February 2012: ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into its 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. These two photographs show the La Silla Observatory in the late 1960s and the present day. You can also examine the differences between the two photographs with our mouseover comparison. The telescopes aren’t the only things that have changed; the cars in the photos also show the passing of time. The Volkswagen 1600 Variant in the first picture has been replaced in the second picture by a Suzuki 4WD. Nowadays, all ESO vehicles on La Silla are white, to improve visibility at night. Standing alone ...
potw1205 — Picture of the Week
A Shadow at Sunrise
30 January 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 3060-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 ...
potw1204 — Picture of the Week
Barred Spiral Galaxy Swirls in the Night Sky
23 January 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 ...
potw1203 — Picture of the Week
ALMA’s Grand Antennas
16 January 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, ...
potw1202 — Picture of the Week
Mapping Dark Matter in Galaxies
9 January 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 ...
potw1201 — Picture of the Week
A Glimpse into the Past — Then and Now at La Silla Observatory
3 January 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 ...
potw1152 — Picture of the Week
Inside Euler's Head — Or how to see a telescope through the walls of its dome
26 December 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 ...
potw1151 — Picture of the Week
Llullaillaco, Clear as Day
19 December 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 ...
potw1150 — Picture of the Week
ALMA's World At Night
12 December 2011: This panoramic view of the Chajnantor plateau, spanning about 180 degrees from north (on the left) to south (on the right) shows the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) ranged across the unearthly landscape. Some familiar celestial objects can be seen in the night sky behind them. These crystal-clear night skies explain why Chile is the home of not only ALMA, but also several other astronomical observatories. This image is just part of an even wider panorama of Chajnantor. In the foreground, the 12-metre diameter ALMA antennas are in action, working as one giant telescope, during the observatory’s first phase of scientific observations. On the far left, a cluster of smaller 7-metre antennas for ALMA’s compact array can be seen illuminated. The crescent Moon, although not visible in this image, casts stark shadows over all the antennas. In the sky above the antennas, the most prominent bright “star” ...
potw1149 — Picture of the Week
The VLT’s Next-generation Laser Launch Telescope
5 December 2011: This telescope is an important new component of the Four Laser Guide Star Facility, which will sharpen the already excellent vision of ESO’s Very Large Telescope (VLT). Four powerful 20-watt lasers, fired to an altitude of 90 kilometres up in the atmosphere, will help the VLT correct the image distortion caused by turbulence in the air. The Netherlands Organisation for Applied Scientific Research (TNO) is developing the launch telescopes through which the laser beams will be fired. The first of these laser launch telescopes — known as the Optical Tube Assembly — is seen here in the cleanroom at TNO’s Van Leeuwenhoek Laboratory in Delft, the Netherlands, having recently held its Acceptance Review. A special anti-reflective coating gives the lens on the telescope a distinctive blue hue. The photograph was taken by Fred Kamphues, who appears on the left. He is project manager for the Optical Tube Assembly, and is also ...
potw1148 — Picture of the Week
A Galaxy Full of Surprises — NGC 3621 is bulgeless but has three central black holes
28 November 2011: This image, from ESO’s Very Large Telescope (VLT), shows a truly remarkable galaxy known as NGC 3621. To begin with, it is a pure-disc galaxy. Like other spirals, it has a flat disc permeated by dark lanes of material and with prominent spiral arms where young stars are forming in clusters (the blue dots seen in the image). But while most spiral galaxies have a central bulge — a large group of old stars packed in a compact, spheroidal region — NGC 3621 doesn’t. In this image, it is clear that there is simply a brightening to the centre, but no actual bulge like the one in NGC 6744 (eso1118), for example. NGC 3621 is also interesting as it is believed to have an active supermassive black hole at its centre that is engulfing matter and producing radiation. This is somewhat unusual because most of these so-called active galactic nuclei ...
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