Picture of the Week

30 December 2019: This Picture of the Week captures the skies above ESO’s Paranal Observatory ablaze with colour — blues, purples, oranges, greens, yellows and reds all mingle together to create this striking view of the Chilean site. One of the Auxiliary Telescopes (ATs) comprising ESO’s Very Large Telescope (VLT) is visible in the foreground, bathed in an eerie yellow-green glow. This AT is just one of the VLT’s four 1.8-metre auxiliaries, which also includes four giant 8.2-metre cousins (Unit Telescopes).The ATs are unique; they are self-contained and, depending on the needs of the observing project, can be repositioned in up to 30 different observing locations along a system of tracks. Acting together as the VLT Interferometer (VLTI), they capture light from celestial objects and send it to the same focal point through a system of mirrors housed within underground tunnels, allowing researchers to observe the cosmos in incredible detail. Comprising eight telescopes ...

23 December 2019: As the year draws to a close, we pause to extend a festive greeting to our community on behalf of everyone here at the European Southern Observatory. We wish you a very merry end of the year and a fruitful 2020! We look forward to sharing it with you all.

16 December 2019: Difficult as it may be, given the view above, when at Paranal Observatory make sure you keep your eyes on the ground — or you might just take a tumble. This Picture of the Week shows an entrance to one of the laboratories beneath the ESO’s Very Large Telescope (VLT) platform, used to carry out an astronomical technique known as interferometry. The VLT is composed of four large Unit Telescopes and four smaller Auxiliary Telescopes (ATs) — two of the latter are imaged here. Astronomers can use various combinations of these telescopes to pool their observing power and, using the technique of interferometry, achieve imaging resolutions much greater than is possible by any of them alone. This clever trick is performed beneath the platform in a network of tunnels filled with specialised equipment to direct and process the light gathered by the telescopes. Paranal Observatory is located in northern Chile ...

9 December 2019: This cloud-strewn new image of RCW 36 (or Gum 20) was captured by ESO’s Focal Reducer and low dispersion Spectrograph (FORS). It shows one of the sites of massive-star formation closest to our Solar System, about 2300 light-years away. Located in the constellation of Vela (The Sails), the RCW 36 emission nebula is only part of an even larger star formation complex, known as the Vela Molecular Ridge. Some areas in the clouds of RCW 36 are dense enough to block out background light, creating patches and wisps of inky black. Despite the dark appearance of these clouds, they are the only places in the Universe in which star formation occurs; clumps of molecular hydrogen and cosmic dust collapse and come together to form stars encircled by small families of planets, as in our own Solar System. FORS is mounted on ESO’s Very Large Telescope, one of the world's most ...

2 December 2019: Seen here, the majestic Milky Way rises above ESO’s La Silla Observatory in Chile, its bright band punctuated by red regions of star formation and dark, weaving filaments of interstellar dust. Two of the site’s telescopes, the 1-metre Schmidt telescope (left) and the MPG-ESO 2.2-metre telescope (right), are are visible as well. While all of the stars in the sky belong to the Milky Way galaxy, we commonly refer to this thick streak across the sky as “the Milky Way”. This is because of our position within our home galaxy: the Solar System sits on one of our galaxy’s spiral arms and is located roughly two-thirds of the distance between the Milky Way’s centre and its peripheries. The galaxy itself is shaped a little like a giant pancake with a bright bulge in the centre, with almost all of its constituent stars, gas, dust, planets, and so on lying within ...

25 November 2019: High up in the outskirts of the Chilean Atacama Desert, in the skies above ESO’s La Silla Observatory, a meteor blazes across the star-studded and dust-streaked Milky Way. This picturesque event had a silent, static onlooker, visible here to the left of the frame: the Swedish-ESO Submillimetre Telescope (SEST). The SEST was built in 1987 on behalf of ESO and the Swedish Natural Science Research Council, and was decommissioned in 2003.For those 16 years it gazed up at some of the darkest and clearest skies in the world. At the time of construction, the 15-metre SEST was the only large telescope in the southern hemisphere designed for submillimetre astronomy. While active, the SEST was used for a broad range of research, including observing the centre of the Milky Way, and studying our galaxy’s two satellites, the Magellanic Clouds. In 1995, SEST observations showed the Boomerang Nebula — ...

18 November 2019: ESO’s astronomical facilities in Chile are hives of activity — or oases! — in the otherwise barren and arid landscape of the Atacama Desert. This hostile and hard-to-reach location may seem like an odd choice for construction, but the Atacama is one of the best sites in the world for astronomy. It has practically no cloud cover, a distinct lack of light pollution, and is the driest non-polar location in the world, receiving under two centimetres of rainfall every year! Chile has hosted ESO’s telescopes since the 1960s, in observatories based at La Silla, Paranal, and Chajnantor Plateau. Shown here is the Visible and Infrared Survey Telescope for Astronomy (VISTA), situated at the Paranal Observatory. Perched atop a mountain adjacent to Cerro Paranal, the home of the flagship Very Large Telescope (VLT), VISTA is the largest telescope in the world designed to survey the sky in near-infrared light (just beyond ...

11 November 2019: The telescopes at ESO’s La Silla Observatory in Chile are on a mission to observe and understand the vast Universe — but there are plenty of interesting natural phenomena far closer to home. One such example is this angelic 22-degree halo. This photo was taken high up in the remote Atacama Desert, but such a sight is visible year-round all over the world. These haloes are formed when light from the Sun or Moon passes through cirrus clouds high up in the Earth’s atmosphere. The tiny ice crystals that make up these clouds act as miniature prisms, changing the direction of the light that passes through them (something known as refraction). Light rays that do this tend to “bunch up” at the angle that represents the least amount of deviation from their original path. For the particular shape of ice crystal lurking within the cirrus clouds, this minimum deviation angle ...

4 November 2019: This seldom-seen perspective offers a true insider’s view of one of ESO’s world-leading telescopes: the VLT Survey Telescope, or VST. The VST is installed at ESO’s Paranal Observatory in Chile. It is the largest telescope surveying the sky in light visible to humans and its cutting-edge design makes it a powerful tool for studying the Universe. From this viewpoint the OmegaCAM instrument — a camera with a large field of view — can be seen front and centre, nestled inside its stabilising control structure. When night falls the telescope’s dome opens and the VST gets to work. The high altitude and arid conditions of the Atacama Desert provide the perfect conditions for astronomical observing, delivering cloud-free skies and very low light pollution for the vast majority of the year. This allows for truly spectacular views of the Milky Way overhead, complete with its array of striking colours, streaks of dark ...

28 October 2019: This strikingly simple and serene view of NGC 1404 — a giant elliptical galaxy located 62 million light-years away in the constellation of Fornax (The Furnace) — hides the galaxy’s cruel reality. NGC 1404 is one of the galaxies comprising the massive Fornax Cluster — and it is slowly falling inwards towards the cluster’s core. As it moves towards the cluster’s large centremost galaxy, NGC 1399, the galaxy’s reserves of hot gas are being forcibly ripped and stripped away, leaving an elongated tell-tale trail of gas in its wake. While not visible in this image, this gas stream can be seen clearly in X-ray images of the galaxy; in time, NGC 1404 will lose most of its hot gas, and therefore its ability to form new stars. ESO’s Very Large Telescope (VLT) captured this image of NGC 1404 with its FORS instrument. The bright foreground star to the lower left ...

21 October 2019: In a remote part of Chile’s Atacama Desert, at an altitude of over 2600 metres, sits Paranal Observatory. In terms of total light-collecting area, it is the largest observatory in the southern hemisphere, and is home to several of ESO’s cutting-edge telescopes. The main peak, visible here directly beneath the eerily tranquil yellow Moon, hosts ESO’s Very Large Telescope (VLT) and the 2.6-metre VLT Survey Telescope (VST). The VLT’s four Unit Telescopes can be seen on top of this peak, next to the smaller Auxiliary Telescopes on the far left and the VST towards the right. As ESO continues to expand its array of telescopes in the southern hemisphere, more space is required for construction! A secondary peak around 1500 metres away from the VLT and VST — on the far right on this image — was chosen as the site for ESO’s Visible and Infrared Survey Telescope for ...

14 October 2019: Like many of ESO’s telescopes, the Danish 1.54-metre telescope at La Silla Observatory in Chile is accompanied by an all-sky camera that transmits views of the site 24/7, allowing anyone and everyone worldwide to see the telescope in action. Viewers can see astronomers and engineers at work, admire breathtaking night-time views of the Milky Way, and — if they’re lucky — spot some of the locals. This rare snap captures a native bird using the all-sky camera as a perch, perfectly unaware that it is blocking the view. The bird’s species remains an unsolved mystery; the image was taken at night so it is likely that the bird was out hunting, which suggests it is a nocturnal species. Despite the high and dry conditions of ESO’s observatories in Chile’s Atacama Desert, the area is home to a wide range of wildlife, such as llama-like Vicuñas, sharp-eyed Andean foxes, majestic birds ...

7 October 2019: This image features a comet located in the outer reaches of the Solar System: comet C/2016 R2 (PANSTARRS). As its name suggests, the comet was discovered in 2016 by the Pan-STARRS telescopes in Hawai’i. The new image seen here was captured by a project based at ESO’s Paranal Observatory in Chile named the Search for habitable Planets EClipsing ULtra-cOOl Stars — or SPECULOOS for short. Comets are balls of dust, ice, gas and rock. When they pass close to the Sun, their ice warms up, turns to gas, and escapes in a process called “outgassing”. This process forms fuzzy envelopes around the comets’ nucleus, called comas, and distinctive tails. Observations from SPECULOOS show that the tail of C/2016 R2 (PANSTARRS) changes dramatically across a single night, making for a dynamic set of images. The image shown here, and accompanying frames in the time-lapse movie, comprise observations taken on 18 January ...

30 September 2019: Using the detailed eyes of the Atacama Large Millimeter/submillimeter Array (ALMA) and ESO’s Very Large Telescope (VLT), astronomers have mapped the intense tails of a cosmic jellyfish: a number of knotty streams of gas spewing outwards from a spiral galaxy named ESO 137-001. This celestial cnidarian is shown here in beautiful detail. The various elements making up this image were captured by different telescopes. The galaxy and its surroundings were imaged by the NASA/ESA Hubble Space Telescope; its tails, which trace streams of hydrogen and show up in hues of bright purple, by the MUSE instrument mounted on the VLT; and bright hotspots of carbon oxide emission from within the system, which show up as flares of orange-red, were spotted by ALMA. These tails are caused by a dramatic phenomenon known as ram-pressure stripping. The space between galaxies in a cluster is not empty, but full of material that acts ...

23 September 2019: This week’s Picture of the Week showcases the bulging heart of the Milky Way as it hangs over the Chajnantor plateau. Located in the Atacama Desert of Chile, this plateau is one of the highest and driest places on Earth. This combination results in ideal conditions to observe millimetre and submillimetre radiation from space, which is usually strongly absorbed by Earth’s atmosphere. It is therefore no surprise that the Chajnantor plateau is home to the spectacularly productive Atacama Large Millimeter/submillimeter Array (ALMA), a state-of-the-art telescope that is studying light from some of the coldest objects in the Universe. Above the intricate dust clouds and the frenzied glow of billions of stars, Mars, Saturn and the star Antares make a distinct triangle in the sky. The fuzzy green object to the left of the frame, nearly drowned out by the spectacular light of the Milky Way, is an interplanetary visitor called ...

16 September 2019: From 4 to 18 August this year, AstroCamp 2019 took place at the Centre for Environmental Education and Interpretation in the Corno de Bico Protected Landscape in northern Portugal. AstroCamp is an astronomy-focused academic programme for secondary school students which aims to bring together students with different backgrounds and life experiences, but with one common passion: astronomy. 18 students aged between 15 and 18 took part in the camp — 11 girls and 7 boys, from Brazil, Germany, Italy, Poland, Portugal, Spain, Sweden and the United Kingdom. Over the course of two weeks, the astronomy enthusiasts took courses on relativity and on the physics of stars, galaxies and the Universe as a whole, observed the dark night skies using both the naked eye and telescopes, and connected online with astronomers and physicists from different countries. They also completed a computational project, working with data from some of the world’s best ...

9 September 2019: This beautiful image features the Milky Way rising over the Residencia at ESO’s Paranal Observatory, which can be seen atop a mountain in the distance. The Residencia is ESO’s private hotel for staff at Paranal, a home away from home for the astronomers, engineers, technicians, and other visitors to the site. Known as an “oasis for astronomers”, the building includes a restaurant, music room, library, swimming pool, and even a sauna to help astronomers to relax between and after their shifts. It was even featured in the James Bond film “Quantum of Solace” (2008). This photograph was taken by ESO Photo Ambassador Petr Horálek, and is a great demonstration of just how artificial light can pollute its environment — the brightness of the Residencia lights seems almost blinding compared to the stars. Artificial light scatters off the particles in our atmosphere and can drown out the night sky. Preserving the ...

2 September 2019: NGC 3351, also known as Messier 95, was first discovered in 1781 by Pierre Méchain, a French astronomer and surveyor who worked alongside Charles Messier. NGC 3351 is a type of galaxy known as a barred spiral galaxy and it is located in the constellation of Leo (The Lion). New observations of this object have shown stellar feedback in action. Stellar feedback is the process of redistributing energy into the interstellar medium (the space in between the stars) within star-forming galaxies. In this particular galaxy, star formation is occurring in the ring surrounding the galaxy nucleus at such a violent rate that massive bubbles of hot gas can actually be seen being ejected. This ejected gas can then contribute (both positively and negatively) to ongoing star formation within the galaxy. The data for this observation were taken with ALMA, the NASA/ESA Hubble Space Telescope and the Very Large Telescope, showing ...

26 August 2019: Snow is a rare sight at Paranal Observatory. However, when it does choose to appear, the remote Chilean landscape transforms into something quite extraordinary and otherworldly. The distant, snow-covered mountain at the centre of the frame is Cerro Paranal, the site of ESO’s Very Large Telescope (VLT). The VLT is made up of four large Unit Telescopes (UTs) — Antu, Kueyen, Melipal, and Yepun — and four smaller Auxiliary Telescopes (ATs). In this image the very tops of two of the UTs can be seen peeking over the mountaintop, alongside the VLT Survey Telescope (VST), which began observing in 2011. This image, taken by ESO Photo Ambassador Gerhard Hüdepohl, captures a truly rare view of Paranal. Precipitation of any kind is very rare in the Atacama Desert; the location is the driest non-polar desert in the world. Some parts of the Atacama have not experienced a single drop of rain ...

19 August 2019: The 12-metre dish of the Atacama Pathfinder Experiment (APEX) cuts a lonely figure in this aerial image of the Chajnantor Plateau in northern Chile (right of the centre). The snow visible in the background alludes to the frigid temperatures found at an altitude of over 5000 metres above sea level. This telescope is located in the arid, dry Atacama Desert, which experiences an average rainfall of only 100 millimetres per year. Since first light in 2004, APEX has contributed much to our understanding of the Universe at submillimetre wavelengths in the areas of star and planet formation, very distant galaxies in the early Universe, and the conditions present in molecular clouds. Among the many astronomical insights APEX has given us, it was the first telescope to detect hydrogen peroxide in space and the first to observe a circumstellar disc around a young massive star. APEX was created from a modified ...