Picture of the Week

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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 ...
potw1147 — Picture of the Week
A Double Green Flash
21 November 2011: At sunset, the sky is often painted with an array of oranges, reds and yellows, and even some shades of pink. There are, however, occasions when a green flash appears above the solar disc for a second or so. One such occurrence was captured beautifully in this picture taken from Cerro Paranal, a 2600-metre-high mountain in the Chilean Atacama Desert, by ESO Photo Ambassador Gianluca Lombardi. Cerro Paranal is home to ESO’s Very Large Telescope. The green flash is a rather rare phenomenon; seeing such a transient event requires an unobstructed view of the setting (or rising) Sun and a very stable atmosphere. At Paranal the atmospheric conditions are just right for this, making the green flash a relatively common sight (see for example eso0812). But a double green flash such as this one is noteworthy even for Paranal. The green flash occurs because the Earth’s atmosphere works like a ...
potw1146 — Picture of the Week
Working at ALMA, Day and Night
14 November 2011: In the foothills of the Chilean Andes, at an altitude of 2900 metres, the Operations Support Facility (OSF) for the Atacama Large Millimeter/submillimeter Array (ALMA) is a hive of activity. This photograph shows engineers moving a heavyweight antenna at night — with the help of a special 28-wheel transporter — and illustrates how work at ALMA continues around the clock. The antenna, one of 25 provided for the ALMA project by ESO, is being moved into position next to antennas from the other ALMA partners to be tested and equipped with highly sensitive detectors. When completed, ALMA will consist of 66 12-metre and 7-metre antennas that will work together as a giant radio telescope observing at millimetre and submillimetre wavelengths. The facility will allow astronomers to study our cosmic origins by probing the first stars and galaxies, and imaging the formation of planets. The telescope is being constructed on Llano ...
potw1145 — Picture of the Week
GRAAL on a Quest to Improve HAWK-I's Vision
7 November 2011: This image shows some of the GRAAL instrument team, inspecting GRAAL’s mechanical assembly in the integration hall of ESO’s Headquarters in Garching bei Munchen, Germany. GRAAL, which will be installed on ESO’s Very Large Telescope (VLT) on Cerro Paranal in Chile, is designed to improve the vision of the VLT’s already excellent HAWK-I camera even further. GRAAL stands for GRound layer Adaptive optics Assisted by Lasers. It will use the technique of adaptive optics to improve the quality of images by compensating for turbulence in the lower layers of the atmosphere, up to an altitude of 1 kilometre. GRAAL will form part of the observatory’s next generation Adaptive Optics Facility (AOF). The VLT already uses a powerful laser beam to create an artificial guide star, 90 kilometres up in the atmosphere. The current adaptive optics systems use this guide star as a reference to remove the effect of turbulence in the ...
potw1144 — Picture of the Week
Twinkle Twinkle Little Star
31 October 2011: A glowing laser shines forth from the European Southern Observatory’s Very Large Telescope. Piercing the dark Chilean skies, its mission is to help astronomers explore the far reaches of the cosmos. ESO Photo Ambassador Gerhard Hüdepohl was on hand to capture the moment in a stunning portrait of modern science in action.  We have all gazed up at the night sky and seen the stars gently twinkle as the Earth’s turbulent atmosphere causes their light to shimmer. This is undoubtedly a beautiful sight, but it causes problems for astronomers, who want the crispest possible views. To help them achieve this, professional stargazers use something that sounds as though it has come from science fiction: a laser guide star that creates an artificial star 90 km above the surface of the Earth. The method by which it achieves this is nothing short of remarkable. The laser energises sodium atoms high in ...
potw1143 — Picture of the Week
Portrait of an Imperfect but Beautiful Spiral
24 October 2011: Not all spiral galaxies have to be picture-perfect to be striking. Messier 96, also known as NGC 3368, is a case in point: its core is displaced from the centre, its gas and dust are distributed asymmetrically and its spiral arms are ill-defined. But this portrait, taken with the FORS1 instrument on ESO’s Very Large Telescope, shows that imperfection is beauty in Messier 96. The galaxy's core is compact but glowing, and the dark dust lanes around it move in a delicate swirl towards the nucleus. And the spiral arms, patchy rings of young blue stars, are like necklaces of blue pearls.   Messier 96 lies in the constellation of Leo (The Lion). It is the largest galaxy in the Leo I group of galaxies; including its outermost spiral arms, it spans some 100 000 light-years in diameter — about the size of our Milky Way. Its graceful imperfections likely ...
potw1142 — Picture of the Week
Stars Dancing Above the VLT
17 October 2011: The night sky above the 2600-metre-high Cerro Paranal in the Atacama Desert in Chile is dark and clear. So clear, that very long sequences of photos can easily be taken without a single cloud obscuring the stars as they rotate around the southern celestial pole. The site is home to ESO’s Very Large Telescope (VLT) array. Its four 8.2-metre Unit Telescopes dominate this image made by Farid Char, a student at Chile’s Universidad Católica del Norte. One of the smaller Auxiliary Telescopes is also visible, hiding in the background in the bottom left corner. But the star of the show is the striking starry sky. Made by combining 450 exposures of 20 seconds each, the image captures the apparent stellar movement during two and a half hours. This movement, signalled by dotted trails, is illusory: the Earth, and not the stars, is rotating as time goes by. The sequence has ...
potw1141 — Picture of the Week
Flying above the ALMA Site: The Operations Support Facility
10 October 2011: This spectacular aerial view shows the ALMA Operations Support Facility (OSF), located 2900 metres above sea level in the foothills of the Chilean Andes, near San Pedro de Atacama. ALMA, the Atacama Large Millimeter/submillimeter Array, is currently under construction on the 5000-metre-high Chajnantor plateau. Such a high altitude site is necessary for ALMA’s array of antennas to observe the Universe in millimetre and submillimetre radiation, but the lack of oxygen makes the Array Operations Site (AOS) a very uncomfortable place for people to work. For this reason, as much of the scientific and technical work as possible takes place at the OSF, which is 2100 metres lower in altitude. The antennas are even controlled remotely from the OSF. In this picture, from the bottom left to the centre right, the North American, the Japanese and the European antenna assembly facilities are clearly distinguishable. In these areas, the antennas are assembled ...
potw1140 — Picture of the Week
VLT Observes the Antennae Galaxies
3 October 2011: A new Very Large Telescope (VLT) image of the Antennae Galaxies gives us what may be the second-best visible-light view yet of this striking pair of colliding galaxies with dramatically distorted shapes. This amazing object takes its name from the long antenna-like "arms" extending far out from the nuclei of the two galaxies, best seen in wider-field images by ground-based telescopes such as the one at this link. This VLT view focuses instead on the galaxies’ nuclei, where the real action is taking place as the two galaxies merge into a single giant galaxy. Spurred by shock waves created by their gravitational wrestling, the two galaxies have become dotted with brilliant blue hot young stars in star-forming regions, surrounded by glowing hydrogen gas, shown here in pink. The two pale yellow blobs are the cores of the original galaxies, shining with the light of old stars and picked out by ...
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