Picture of the Week

11 April 2016: This Auxiliary Telescope at the Very Large Telescope (VLT), located at the Paranal Observatory in Chile, looks to be pointing at the greenish emerald glow of the comet 252P/LINEAR high above it. Discovered in April 2000, 252P/LINEAR is a relative newcomer to the inner Solar System, traveling between the orbit of Jupiter and the orbit of Earth. A couple of days ago, in March 2016, it passed particularly close to the Earth, at a distance of only 5.2 millions kilometers, ranking as the fifth closest recorded passage of a comet. It can still be admired in the southern hemisphere. The green colour arises from fluorescing carbon-based gas surrounding the comet. This gem of a picture was taken by the ESO Photo Ambassador Babak A. Tafreshi. He has just started out on ESO���s Fulldome Expedition, during which he will be taking more spectacular pictures from ESO���s observatories and of the southern ...

4 April 2016: The faint light extending up from the horizon just below centre of this photo is known as zodiacal light, caused by sunlight scattering from cosmic dust in the plane of our Earth���s orbit. A second band of light can be seen at the horizon on the lower left. This red light is airglow, produced by the Earth���s atmosphere. Airglow is caused by processes taking place in the upper atmosphere, including cosmic rays, recombining photoionized atoms, and various chemical reactions between oxygen, nitrogen, hydroxyl, sodium, and lithium atoms. The third and final band is the Milky Way, our home galaxy, high in the sky. This band consists of billions of stars of all kinds. Many of them are hidden to the human eye behind large layers of interstellar dust, giving the Milky Way its characteristically mottled look. At the centre of the image stands ESO Photo ambassador Babak Tafreshi, watching the ...

28 March 2016: Deep in the Chilean Desert, astronomers staying at ESO���s La Residencia, the VLT Observatory's hotel, witness a skyscape like few others on Earth. Designed by the German architects Auer+Weber+Assoziierte, La Residencia provides an oasis for those working at ESO���s Paranal Observatory. The Atacama Desert is one of the harshest landscapes imaginable. Extreme dryness, intense ultraviolet radiation from the Sun, and high altitude are a normal part of everyday life. However, come nightfall, La Residencia experiences some of the best observing conditions in the world. La Residencia and ESO���s Very Large Telescope (VLT) ��� housed at the Paranal Observatory ��� are far from sources of light pollution, and experience exceptionally clear atmospheric conditions. On moonless nights, the sky can be so clear and dark that light from the Milky Way casts a shadow on the ground! These factors permit high quality scientific observations to be made as well as offering amazing ...

21 March 2016: The dark patch snaking across this spectacular image of a field of stars in the constellation of Ophiuchus (The Serpent-bearer) is not quite what it appears to be. Although it looks as if there are no stars here, they are hidden behind this dense cloud of dust that blocks out their light. This particular dark cloud is known as LDN 1768. Despite their rather dull appearance, dark nebulae like LDN 1768 are of huge interest to astronomers, as it is here that new stars form. Inside these vast stellar nurseries there are protostars ��� stars at the earliest stage of their lives, still coalescing out of the gas and dust in the cloud. Protostars are relatively cold and have not yet begun to produce enough energy to emit visible light. Instead, they emit radiation at submillimetre wavelengths, which human eyes cannot see. Luckily, unlike visible light, light at submillimetre wavelengths ...

14 March 2016: This picture was taken just before dawn at the La Silla Observatory, in outskirts of the Chilean Atacama Desert. A layer of orange hovering over the horizon announces the imminent arrival of the Sun. These first hints of daylight are kissed by the Milky Way, which stretches out across the entire night sky. This view of our home galaxy is covered with dark patches, formed from dust particles blocking the light behind them. In front of this cosmic scenery you can see some of the observatory���s telescopes. The closest is the Swedish���ESO Submillimetre Telescope (SEST), whose dish measures 15 metres across. It was decommissioned in 2003 and replaced by the Atacama Pathfinder EXperiment telescope (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA). On the plateau in the background stands the ESO 3.6-metre telescope, with the Coud�� Auxiliary Telescope (CAT) right behind it. SEST seems to be pointing at an extremely ...

7 March 2016: In this picture, our home galaxy the Milky Way stretches across the sky above the landscape of the Chilean Andes. In the foreground, the roads of ESO���s La Silla Observatory are packed with state-of-the-art astronomical telescopes pointing towards, and far beyond, the Milky Way. Several multinational telescopes are captured in this frame. The ESO 3.6-metre telescope stands on the central pedestal and is mounted with the High Accuracy Radial velocity Planet Searcher (HARPS) ��� the best exoplanet finder on Earth. Just next to the main dome, the smaller one once hosted the Coud�� Auxiliary Telescope (CAT) which used to feed the powerful Coud�� Echelle Spectrograph; they are now both decommissioned. At the foot of this pedestal lies the French Rapid Action Telescope for Transient Objects (TAROT) which follows up on highly energetic events called gamma-ray bursts. These are also studied by the Swiss 1.2-metre Leonhard Euler Telescope in the dome ...

29 February 2016: Pictured here at sunset is one of the four Auxiliary Telescopes (ATs) of the Very Large Telescope Interferometer (VLTI), shown at ESO's Paranal Observatory. The faint crescent Moon can be seen hanging above the round enclosure of the telescope. Together with four Unit Telescopes (UTs) that make up the Very Large Telescope, these four ATs complete the VLTI. Unlike the UTs, which are fixed, each of the four 1.8-metre ATs are movable and can be relocated to 30 different stations along the platform to create a wide baseline of up to 200 metres. This allows the VLTI to act as one large telescope of this size via a technique called interferometry ��� combining the light from several smaller telescopes to increase the resolution of the telescope. In the case of VLTI, this provides milliarcsecond angular resolution ��� equivalent to a span of two metres as far away from us as ...

22 February 2016: This image is unreal ��� literally! Rather than being a single picture, it was created by combining two separate photographs together, and shows the January sky as seen from both hemispheres. The skilled photographer was ESO Photo Ambassador Petr Hor��lek. Petr shot the upper part of the image from ESO���s Paranal Observatory in Chile and the lower part from the Slovakian village of Oravska Lesna, before combining the two to form this striking composite. One arm of the distinctive X-shaped structure spreading from the top right to the bottom left of the frame is the lane of the Milky Way. The other diagonal comprises glowing columns of zodiacal light. In the centre of the image, is one of the four small 1.8-metre Auxiliary Telescopes that make up part of ESO's Very Large Telescope (VLT). A significant glow can be seen in the lower part of the image, caused by light ...

15 February 2016: This striking photograph from Yuri Beletsky captures many wonders ��� both terrestrial and astronomical ��� across an incredible distance scale. In the immediate foreground looms ESO���s VISTA survey telescope. This 4.1-metre telescope scans the skies in infrared light, picking out astronomical objects of interest so that they can be studied by the four 8.2-metre Unit Telescopes of ESO���s Very Large Telescope (VLT) facility. This facility can be seen on the mountaintop to VISTA���s right, about a kilometre up the road. In the sky above VISTA a luminous and dark-ribboned band runs from lower left to top right. This is the disc of the Milky Way, seen edge-on and looking inward toward the galactic core. Although we cannot see all the way to the core with our unaided eyes, we have gauged its distance as about 30 000 light-years from us. That distance works out as about 280 quadrillion kilometres, or ...

8 February 2016: You may be wondering what a truck has to do with astronomy. Well, this is no ordinary truck ��� it is an ALMA transporter! At 20 metres long and 10 metres wide, this is one of a pair of custom-designed vehicles used to transport the 66 antennas that make up the Atacama Large Millimeter/submillimeter Array (ALMA). From its home at 5000 metres above sea level, high in Chile���s Atacama Desert, ALMA delivers a unique view of the low temperature Universe, allowing astronomers to study how stars form in unprecedented detail. The trucks ��� this one is called Lore, its sibling is Otto ��� move each antenna along the 28-kilometre road from the construction area at just below 3000 metres above sea level, up to the main telescope site, around 2000 metres higher. They are then used to move the antennas into different configurations corresponding to the different observing modes of ...

1 February 2016: This picture of the week shows the spiral galaxy NGC 986 in the constellation of Fornax (The Furnace). The galaxy, which was discovered in 1826 by the Scottish astronomer James Dunlop, is not often imaged due to its proximity to the famous and rich Fornax Cluster of galaxies. Which is a shame, as this galaxy is not only a great scientific object, but also very pretty. The galaxy is about 56 million light-years away and seen almost perfectly from the top, or ��� as astronomers say ��� face-on. This allows us to see the two main spiral arms and also a central bar-shaped structure, composed of stars and dust, which makes it a barred spiral galaxy. Astronomical surveys have shown that about two thirds of all spiral galaxies contain a bar, including the Milky Way. This makes NGC 986 the perfect place to study the structure of galaxies and find ...

25 January 2016: In the sky above ESO's La Silla Observatory, the Southern Cross is clearly visible just to the right of the dome of the Danish 1.54-metre telescope, and to the lower right of the image, two stars sparkle in the amazingly dark sky. From right to left, these are Alpha and Beta Centauri. Alpha Centauri is a multiple star, the nearest star system to Earth. A little closer to Earth than the bright components of Alpha Centauri, and invisible to the naked eye, is Proxima Centauri, the third star belonging to this multiple star system. It is our closest neighbour, at a distance of just 4.2 light-years. Previous observations have provided tantalising, but subtle, hints of a small companion orbiting this red dwarf star. An observing campaign that started in January 2016 will make a more sensitive search for the telltale wobbles in the dwarf star���s orbital motion that might reveal ...

18 January 2016: The Milky Way contains hundreds of billions of stars. However, the star at the centre of this image still manages to be very unusual ��� no mean feat! A Brazilian���American team led by Jorge Melendez, from the University of S��o Paulo used two of ESO���s telescopes in Chile to discover that this star, named 2MASS J18082002���5104378, is a rare relic from the Milky Way���s formative years. As such, it offers astronomers a precious opportunity to explore the first stars that sprung to life within our galaxy. 2MASS J18082002���5104378 was spotted in 2014 by ESO���s New Technology Telescope (NTT). Follow-up observations using ESO���s Very Large Telescope (VLT) discovered that, unlike younger stars such as the Sun, this star shows an unusually low abundance of what astronomers curiously call metals ��� elements heavier than hydrogen and helium. In fact, it is so devoid of these elements that it is known as an ...

11 January 2016: This picture, taken at the La Silla Observatory in Chile, shows the full Moon low in the purple sky, a photographer crouching on the rocks, and the New Technology Telescope (NTT) perched on a hilltop. This image depicts the three things we need for observational astronomy: An object to observe, a telescope to observe it, and a person to make sense of the observations. The Moon is the closest celestial body to Earth and orbits at a distance of 400 000 kilometres as our only natural satellite. Despite the aesthetic glow of the full Moon in this image, the Moon is not a great friend to astronomers. Sunlight that reflects off the lunar surface causes light pollution and makes it harder to observe more distant and very faint objects. Light pollution does not, however, bother the man admiring the view here. This is Babak A. Tafreshi, one of ESO's Photo ...

4 January 2016: These friendly looking creatures, photographed in front of the ESO 3.6-metre telescope at the La Silla Observatory, are Guanacos. Guanacos, alongside the Vicu��a, are one of two types of wild camelid native to this region of northern Chile. Reaching between one and two metres in length (from their heads to their tails) and weighing up to 120 kilograms, guanacos are one of the largest land mammals in Chile. These intrepid adventurers can be found in Bolivia, Paraguay, Argentina, and throughout the Andes: from Tierra del Fuego in the extreme south of Chile all the way up to Peru. Thriving on the feasts of the desert flora, guanacos enjoy mushrooms, grasses, leaves, trees and even some types of cactus flowers as part of their diets. Guanacos and vicu��as are no stranger to ESO���s facilities in the Atacama Desert. In February 2014 a vicu��a fawn was rescued by ESO staff when it ...

28 December 2015: Modern science and the spectre of ancient man coexist in this thought-provoking image of a petroglyph near the site of ESO���s La Silla Observatory in Chile. A petroglyph is an ancient stone engraving, examples of which can be found scattered across the globe. In some places they can date back as far as 40 000 BCE, but the one pictured here is much more recent. Upon the face of the stone, the images of men are depicted alongside llamas or other similar wild camelids. The native nomadic people of the Atacama Desert in Chile would have followed herds of these animals across the largely arid and inhospitable land before they adopted a sedentary culture, creating desert oases where they bred camelids. The pale glow of the stars over and beyond the mountain ridge and the silhouette of one of La Silla���s telescopes frame the passing of the centuries and the ...

21 December 2015: Season���s Greetings on behalf of everyone at the European Southern Observatory! We wish you a jolly end of the year and a fruitful 2016! Links Christmas card 2015

14 December 2015: This fetching cloud of gas was imaged by the ESO Faint Object Spectrograph and Camera (EFOSC2) at ESO's La Silla Observatory. It can be found nestled in the busy constellation of Centaurus in the skies of the southern hemisphere. The cloud of gas ��� named NGC 3699 ��� is a planetary nebula, It is distinguished by an irregular mottled appearance and a dark rift, which roughly bisects it. These objects, despite the name, have nothing to do with planets and are created in the final stages of the evolution of stars similar in mass to the Sun. The name "planetary nebula" arises from the time of their discovery by William Herschel, when they appeared in the telescopes of the time as rounded objects similar in looks to the planets. Towards the end of their lives, stars like the Sun exhaust the supply of hydrogen in their cores, putting a stop ...

7 December 2015: This stunning panorama shows the Milky Way galaxy arching above the platform of ESO's Very Large Telescope (VLT) on Cerro Paranal, Chile. At 2635 metres above sea level, Paranal Observatory is one of the very best astronomical observing sites in the world and is the flagship facility for European ground-based astronomy. The extent of our galaxy's cloudy and dusty structure can be seen in remarkable detail as a dim glowing band across the observation deck. From Earth, we see the Milky Way as a band across the sky because from our vantage point in one of its spiral arms we are seeing its disc-shaped structure edge-on as we peer towards its centre. Our galaxy is surrounded by several smaller satellite galaxies. Prominent here, to the left, are the Small Magellanic Cloud and Large Magellanic Cloud ��� dwarf galaxies which are members of our Local Group of galaxies. The VLT consists ...

30 November 2015: In this wonderful high definition, singe-exposure image taken during the ESO Ultra HD Expedition, three deep sky objects seem to shine in front of the dish of one of the Atacama Large Millimeter/submillimeter Array (ALMA) high-precision antennas. The most striking feature is the reddish Carina Nebula, also known as NGC 3372. It is a large cloud of gas, mostly hydrogen, in which star formation has recently taken place. The short-lived massive blue stars forged within the nebula emit copious amounts of ultraviolet radiation, which then ionises the surrounding gas and causes the hydrogen atoms to glow with a characteristic red colour. Eventually supernova explosions and strong stellar winds from the most massive stars will disperse the gas of the Carina Nebula, leaving behind one or more clusters of stars. Two such star clusters, known as NGC 3532 and IC 2602, can be seen respectively to the top right and top ...