Picture of the Week

27 January 2020: In this photograph, taken by ESO Photo Ambassador Babak Tafreshi, a slice of fiery colour streaks along the horizon near Paranal Observatory in northern Chile, bathing the four Unit Telescopes of the Very Large Telescope (VLT) in a soft, peachy glow. The Milky Way appears to soar directly up from one of the Unit Telescopes, bounded on either side by a spectacular array of stars — including Sirius, which dazzles at the top of the image. Part of Canis Major (The Greater Dog), Sirius is the brightest star in the sky and is actually a binary system, consisting of a main-sequence star (Sirius A, a star in stable “adulthood” that is burning nuclear fuel) and a white dwarf (Sirius B, the dense corpse of a star that ran out of fuel long ago). Wander down the edge of the Milky Way, and you might spy a small group of bright ...

20 January 2020: The Milky Way contains many regions of starbirth — areas where new stars are springing to life within collapsing clumps of gas and dust. One such region, named Gum 26, is shown here as imaged by the FORS instrument on ESO’s Very Large Telescope in Chile. Gum 26 is located roughly 20,000 light-years away in the southern constellation of Vela (The Sails). It is something known as an HII region or emission nebula, where the intense ultraviolet radiation streaming from newly-formed stars ionises the surrounding hydrogen gas, causing it to emit a faint pinkish glow. By catching new stars “pink-handed” in this manner, astronomers can learn more about the conditions under which stars arise, and study how they influence their cosmic environment. This image was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, ...

13 January 2020: Once used as the otherworldly lair for a James Bond villain, the ESO Residencia usually serves a far less sinister purpose! Since construction was completed in 2002, it has been a home from home for the astronomers, engineers and technicians working at ESO’s Paranal Observatory in Chile. The sleek building sits 2400 metres above sea level in the Mars-like Atacama Desert, just a few kilometres from Cerro Paranal — the mountain that hosts ESO’s Very Large Telescope (VLT) and Visible and Infrared Survey Telescope for Astronomy (VISTA). During the day the hotel is bathed in natural sunlight, which enters the building via a huge 35-metre-diameter dome on the roof. Seen here at night, the glass of the dome is beautifully illuminated beneath the Milky Way’s kaleidoscopic arch of blues, reds and pinks. Two neighbouring galaxies — the Large and Small Magellanic Clouds — can be seen as white smudges beneath ...

6 January 2020: Compared to their more intricate spiral cousins, elliptical galaxies resemble soft, hazy clouds. These galaxies have smooth, undefined boundaries, and bright cores surrounded by a fuzzy, diffuse glow. However, looks can be deceiving. At least 10% of ellipticals extend much further out into the cosmos than you might expect, and possess a range of far finer structures than first meets the eye — features such as loops and shells. Located around 100 million light-years away in the constellation of Pisces (The Fish), the galaxy to the upper-left of this image is named NGC 474. It is a stunning example of a shell elliptical galaxy; enormous wispy tails flick around the galaxy’s main body, while the inner structure is formed of a series of nested concentric rings. In fact, the full extent of the galaxy cannot even be contained in this field of view. The tendril-like outer regions of NGC 474 ...

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 ...