Picture of the Week

17 October 2016: Located some 5000 metres above sea level in Chile, the Array Operations Site (AOS) of the Atacama Large Millimeter/submillimeter Array (ALMA) boasts striking views of the Atacama Desert through its many windows. The AOS is the basecamp for the everyday routine operations of the ALMA facility and the second highest building in the world. The AOS Technical Building also houses the ALMA correlator — the highest-altitude supercomputer in the world! The air is so thin at this altitude that the correlator’s fan system requires twice the usual airflow to keep it cool. Construction of the AOS Technical Building started in October 2005, and all interior work was completed in summer 2007. This image shows a view from the exterior of the building, while this video shows an aerial shot taken during ALMA’s construction.

10 October 2016: This image shows the Operations Support Facility (OSF) for the Atacama Large Millimeter/sub-millimeter Array (ALMA) with the dazzling Moon above and two 12-metre antenna dishes in the foreground. The OSF, located at 2900 metres above sea level in the Chilean Andes, is a hub of ALMA-related activity. As well as housing staff and contractors, the facility hosts all the scientific operations related to the array’s daily operation. The two antennas pictured here, for example, were brought back from their observational site to check their functionality as they sit on special calibration pads. Such tests check the computers and motors and ensure that the antenna surfaces are accurate to less than the thickness of a human hair, and can be pointed precisely enough to spot a golf ball sitting 15 kilometres away. Once these antennas have completed their check-up, they will rejoin their counterparts on the Chajnantor Plateau at 5000 metres ...

3 October 2016: This beautiful image, captured with the Atacama Large Millimeter/submillimeter Array (ALMA) features a protoplanetary disc surrounding the young star Elias 2-27, some 450 light years away. ALMA has discovered and observed plenty of protoplanetary discs, but this disc is special as it shows two distinct spiral arms, almost like a tiny version of a spiral galaxy. Previously, astronomers noted compelling spiral features on the surfaces of protoplanetary discs, but it was unknown if these same spiral patterns also emerged deep within the disc where planet formation takes place. ALMA, for the first time, was able to peer deep into the mid-plane of a disk and discovered the clear signature of spiral density waves. Nearest to the star, ALMA found a flat disc of dust, which extends to what would approximately be the orbit of Neptune in our own Solar System. Beyond that point, in the region analogous to our Kuiper ...

26 September 2016: Taken from inside the dome of the fourth Unit Telescope of ESO’s Very Large Telescope (VLT), this spectacular shot from ESO Photo Ambassador Yuri Beletsky captures the VLT’s Laser Guide Star (LGS) in action. The LGS, located on top of the 1.2-metre secondary mirror of Unit Telescope 4, is part of the VLT’s adaptive optics system. By creating a glowing spot — an artificial star — in the Earth’s atmosphere at an altitude of 90 kilometres, the light coming back from the laser can be used as a reference to remove the effects of atmospheric distortion. This allows the telescope to produce astronomical images almost as sharp as if the telescope were in space. The plane of the Milky Way, seemingly pierced by the laser as it soars above the open dome of the telescope, is rippled with dark clouds of interstellar dust that block visible light. However, thanks to ...

19 September 2016: ESO’s various observatory sites in Chile — Paranal, La Silla, Chajnantor — boast enviably low levels of light pollution. However, the skies overhead are rarely pitch-black! As shown in this image of Paranal Observatory, the skies regularly display a myriad of colours and astronomical sights, from the plane of the Milky Way shining brightly overhead to the orange-hued speck of Mars (left), the starry constellations of Scorpius and Orion, and the magenta splash of the Carina Nebula (upper middle). Despite the remote location there are also occasional signs of human activity, for example the sequence of lamps seen in the centre of the frame. These faint lights illuminate the route from the Very Large Telescope (VLT) to the Visible and Infrared Survey Telescope for Astronomy (VISTA) where this image was taken. Due to the highly sensitive camera this photograph also showcases a mysterious phenomenon called airglow. The night sky is ...

12 September 2016: This week’s picture was taken by ESO Photo Ambassador Babak Tafreshi at ESO’s La Silla Observatory. The bright lane of the Milky Way can be seen streaking across the skies above the Chilean Atacama Desert, beneath which sits the New Technology Telescope (NTT), one of the ten active telescopes located at the observatory. La Silla is the oldest observation site used by ESO — it has been an ESO stronghold since the 1960s. The site houses a number of telescopes, two of which are operated solely by ESO: the aforementioned NTT, the star of this image, and the 3.6-metre ESO telescope. Joining this duo are many other collaborative telescopes, operated by various ESO Member States — the Swiss 1.2-metre Leonhard Euler Telescope, the Rapid Eye Mount (REM) telescope, the TAROT gamma-ray-burst chaser, the planet-hunting TRAPPIST, the MPG/ESO 2.2-metre telescope, the ESO 1-metre Schmidt telescope, the ESO 1-metre, and the Danish ...

5 September 2016: The colour blue has many associations — coldness, sadness, serenity. However, the colour holds a completely different meaning for astronomers, as demonstrated by the edge-on spiral galaxy Messier 98. Messier 98, also known as NGC 4192, is located approximately 50 million light-years away in the constellation of Coma Berenices (Berenice's Hair). In this spectacular image from ESO’s New Technology Telescope (NTT), the galaxy’s perimeter, rippled with gas and dust, is dotted with pockets of blueish light. These are regions filled with very young stars, which are so hot that they glow with a bright blue hue. These young stars are burning at such high temperatures that they are emitting fierce radiation, burning away some of the dense material that surrounds them. In total, Messier 98 is thought to contain one trillion stars! The NTT is a 3.58-metre telescope at the La Silla Observatory, which pioneered the use of active optics ...

29 August 2016: High up in the Chilean Atacama Desert, pioneering feats of human engineering collide with the majestic beauty of the natural world. This image shows ESO’s La Silla Observatory, where domes housing some of the most advanced astronomical instruments in the world sit beneath a sky shimmering with stars. All of these stars belong to our home galaxy, the Milky Way. The Milky Way contains billions of stars, arranged in two strikingly different structures. The roughly spherical halo component, consisting mainly of older stars, appears in this image as the background of stars scattered across the sky. The second component is a thin disc made up of younger stars, gas and dust. We see this as a dense, bright, and visually stunning band running almost vertically across the sky. Pockets of dust block out the light from stars behind, giving the band a mottled appearance. The bright concentration in the band ...

22 August 2016: An unusual type of tourist is seen visiting ESO’s La Silla Observatory in this stunning wide-angle photograph taken in January 2015. Captured by ESO Photo Ambassador Petr Horálek, Comet C/2014 Q2 (Lovejoy) appears to streak across the sky (centre left of the image), sneaking past the two telescopes below: ESO’s 3.6-metre telescope (left) and the Swedish-ESO Submillimetre Telescope (SEST). Like most comets, Comet Lovejoy enjoys a long, elliptical and eccentric orbit around the Sun. It entered the inner Solar System for the first recorded time in 2014, and reached perihelion — its closest approach to the Sun — on 30 January 2015. The distance between the Earth and the Sun is defined as 1 astronomical unit (au), or just under 150 million kilometres; Comet Lovejoy came within 1.29 au of our star, placing it between the orbits of Earth and Mars (1.52 au). This image displays the characteristic soft green ...

15 August 2016: These images show the edge of the vast molecular cloud that lies behind the Orion Nebula, 1400 light-years from Earth. The image of the left shows a wide-field view of the region, as seen with the HAWK-I instrument, installed at the Very Large Telescope. A small region is highlighted with a white rectangle, and the rightmost image shows that region in stunning fiery detail, observed with the Atacama Large Millimeter/submillimeter Array (ALMA). As well as producing beautiful images, molecular clouds are of great interest to astronomers. The clouds are stellar nurseries and at their edge atoms react and form molecules by key astrochemical processes. With the ALMA observations scientists were able to resolve this transition from atomic to molecular gas at the border of the Orion molecular cloud. As Orion is the nearest massive star-forming region it is the ideal target to find out more about these astrochemical processes, and ...

8 August 2016: Illuminated only by the impressive nighttime sky, one of ESO’s Very Large Telescope (VLT) Unit Telescopes is an imposing feature in this Picture of the Week. The VLT is one of the largest and most sophisticated astronomical installations in the world. It consists of four identical Unit Telescopes, each with a main mirror of 8.2 metres in diameter. While each is a large telescope in its own right, by combining the light from all telescopes on the platform — a configuration known as an interferometer — the array in its longest baseline can resolve celestial objects 25 times finer than is possible by using one of the telescopes on its own. The VLT is situated 2635 metres above sea level in Chile’s Atacama Desert, where the amount of water vapour in the atmosphere is low enough to permit the VLT to observe infrared, as well as visible, light. The spectacular ...

1 August 2016: Science and art unite in this beautiful photograph, taken in Chile’s Atacama Desert by ESO Photo Ambassador Adhemar M. Duro Jr. To create this visual masterpiece Adhemar pointed his camera at the sky’s south pole, the point at the centre of all the bright arcs and circles. All the stars in the night sky revolve around this point. Over a period of several hours, this motion creates star trails, with each individual star tracing out a circle on the sky. These trails display the various brightnesses and colours of each star, creating a captivating scene! Towards the top left of the image, you can see a short, bright streak of light cutting across the trails — this is caused by a meteor, burning up in a flash of light as it enters Earth’s atmosphere. The desert’s harsh and arid landscape, illuminated here by the light from the stars themselves, is ...

25 July 2016: Each of the thousands of spots in this new image represents a distant star, and the glittering blue holes reveal glimpses of our neighbouring galaxies, the Large and Small Magellanic Clouds. Although this image looks as if it was made on a large scale telescope it was in fact captured from ESO’s La Silla Observatory using a portable setup consisting of a SBIG STL-11000M CCD camera and a Canon prime lens. It was presented in a scientific paper alongside state-of-the art simulations, in an exciting example of how a small camera, a fast lens, a long exposure time and one of the world’s best astronomical sites can reveal huge faint features better than even a big telescope. This deep image was captured using the LRGB method, and provides an insight into the actual process of creating spectacular astrophotography. Many challenges face those attempting to photograph the night sky, including interference ...

18 July 2016: In this image we see a rare sight — water in the Atacama Desert! Reflected on the water’s calm surface we can see the familiar sight of Cerro Paranal, home to ESO’s Paranal Observatory. This desert is one of the driest and most inhospitable places on Earth. The average rainfall in the Cerro Paranal region is less than 10 millimetres per year, indicating that this photograph was taken just after a period of rare rainfall in the area. Soon after the image was taken, the temporary lagoon evaporated swiftly, leaving the valley floor as dry and desiccated as ever. However, what is arguably bad for the minimal flora and fauna of the region is excellent for astronomers. The lack of rainclouds and the dry air allow Paranal astronomers to observe all year round. With over 300 clear nights per year, the Atacama Desert is one of the best sites in ...

11 July 2016: This stunning ultra high definition panorama, taken by ESO Photo Ambassador Petr Horálek, shows the Milky Way galaxy arching above ESO’s La Silla Observatory in Chile. La Silla is located at the southern edge of the Atacama Desert, from where the observatory’s numerous telescopes observe the night sky — one of the darkest on the Earth — perched 2400 metres above sea level, and so making the most of the unrivalled atmospheric conditions at the site to reveal the cosmos in remarkable detail. This image is certainly no different! Our galaxy’s cloudy and dusty structure appears as a brilliant and glowing coronet above the open dome of the MPG/ESO 2.2-metre telescope, which appears to be gobbling up the bright smudge of the Large Magellanic Cloud. Various clouds and nebulae, including the well-known Gum Nebula, stand out against the dark sky in the central–upper part of the image, shining in a ...

4 July 2016: To take this Picture of the Week, ESO Photo Ambassador Adhemar Duro stopped by the roadside en route to one of ESO’s observing sites in Chile. This road winds up to the Atacama Large Millimeter/submillimeter Array, ALMA, located at an altitude of 5000 metres. Due to the image’s long exposure time, the stars trace out circles on the night sky as they orbit the southern celestial pole, located at the centre of the image. Atop the celestial pole the Small and Large Magellanic Clouds — two satellite galaxies of the Milky Way, visible only in the southern hemisphere — can be seen as diffuse bluish clouds. On the left side of the image, an area densely populated by stars marks the centre of the Milky Way. Even though the image was taken in the remote Atacama Desert, the distant lights of the small town San Pedro de Atacama are visible ...

27 June 2016: This image transports you to the most advanced visible-light astronomical observatory in the world: the Very Large Telescope (VLT), located at ESO’s Paranal Observatory in Chile. The shadowy figure gazing at the dark skies is photographer Babak Tafreshi, as captured by his fellow ESO Photo Ambassador Petr Horálek. For a moment, place yourself in Babak’s — or indeed Petr’s — shoes. Here, you are king of the cosmos. The site is silent, dark, still. You stare up at the pristine Chilean night sky, which, with its extremely low levels of both light pollution and water vapour, offers spectacular nighttime scenery to delight any astrophotographer or stargazer. With your trusty camera on hand, a night of amazing photo opportunities lies ahead; you anticipate spending clear hour after clear hour documenting the heavens, with no fear of cloudy weather appearing, uninvited, to spoil the view. The Large Magellanic Cloud is visible at ...

20 June 2016: This Picture of the Week illustrates the remarkable capabilities of SPHERE (the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument), a planet-hunting instrument mounted on ESO’s Very Large Telescope (VLT) in Chile: It shows a series of broken rings of dust around a nearby star. These concentric rings are located in the inner region of the debris disc surrounding a young star named HD 141569A, which sits some 370 light-years away from us. In this image we see what is known as a transition disc, a short-lived stage between the protoplanetary phase, when planets have not yet formed, and a later time when planets have coalesced, leaving the disc populated only by any remaining — and predominantly dusty — debris. What we see here are structures formed of dust, revealed for the first time in near-infrared light by SPHERE — at a high enough resolution to capture remarkable detail! The area shown in ...

13 June 2016: Astronomers hunt for planets orbiting other stars (exoplanets) using a variety of methods. One successful method is direct imaging; this is particularly effective for planets on wide orbits around young stars, because the light from the planet is not overwhelmed by light from the host star and is thus easier to spot. This image demonstrates this technique. It shows a T-Tauri star named CVSO 30, located approximately 1200 light-years away from Earth in the 25 Orionis group (slightly northwest of Orion’s famous Belt). In 2012, astronomers found that CVSO 30 hosted one exoplanet (CVSO 30b) using a detection method known as transit photometry, where the light from a star observably dips as a planet travels in front of it. Now, astronomers have gone back to look at the system using a number of telescopes. The study combines observations obtained with the ESO’s Very Large Telescope (VLT) in Chile, the W. ...

6 June 2016: In this picture, the enclosure for ESO’s New Technology Telescope (NTT) has opened its angled doors to reveal a long slice of the southern sky. The sky is freckled by stars, while the moon lights up the inner walls of the NTT dome, casting a shadow over the 3.6-metre telescope. At the top of the telescope we can make out the secondary mirror cell of the telescope, held in a ring structure and supported on struts above the primary mirror. One of the NTT’s remarkable aspects is that it employs active optics, in which the primary mirror is flexible and its shape is actively adjusted during observations by actuators to preserve the optimal image quality. The position of the secondary mirror is also actively controlled in three directions. This technology, developed by ESO, is nowadays applied to all major modern telescopes, such as the Very Large Telescope at Cerro Paranal ...