Picture of the Week

5 December 2016: The most massive galaxies in the Universe host supermassive black holes at their centres. These truly colossal black holes chew up surrounding material at astonishing rates, expelling huge amounts of radiation as they do so and glowing as some of the brightest objects in the known Universe! Despite their incredible distances from Earth, the regions surrounding these black holes shine so brightly that their appearance is similar to that of stars in our own galaxy, the Milky Way. Some of these objects, known as quasi-stellar-objects or quasars for short, are useful tools to help us better understand the cosmos. Because they lie so far away, there is plenty of intervening space between our telescopes and a target quasar. This space is not empty; it is filled with intergalactic medium, which mostly comprises clouds of gas — mainly hydrogen and helium, but also with hints of other elements — that absorb ...

28 November 2016: The famously dry Atacama Desert may seem like an odd place for the Moon to take a dip — but in this intriguing image, taken by ESO Photo Ambassador Petr Horálek, it appears to do just that! Initially high, the crescent Moon slowly descends through the clear Chilean sky, before hitting the thickest parts of the atmosphere right above the horizon. It was here that a “rare theatre” began, said Horálek. The thin sliver of the Moon was optically distorted into a “weird, snaky shape” as its light passed through layers of different air densities, caused by different pressures, temperatures and humidities. The Moon lost its smooth curves and instead appeared as a rippling and squiggly zig-zag — “as if it were swimming”. The effect of the closely spaced layers in the atmosphere caused different parts of the Moon’s image to be refracted differently as it disappeared below the horizon. ...

21 November 2016: As the Sun sets on another day at La Silla, the observatory’s staff members are able to start doing what they do best — observing and exploring the night sky! La Silla was ESO’s first observatory, and remains one of the most productive observatories in the world. This photograph captures the last few rays of sunlight, producing a striking blend of orange, red and yellow close to the horizon. More prominent, however, are the bright star trails streaking and curving through the sky. Each of these trails is formed by the motion of an individual star, captured over a long exposure time. Vehicles also form light trails from their rear headlights as they move, lighting up the network of roads throughout the region. This picture was taken by ESO Photo Ambassador Roger Wesson. To show both twilight and the growing star trails in the same image, Wesson combined 763 different ...

14 November 2016: The Atacama Large Millimeter/submillimeter Array (ALMA) sits high up on the Chajnantor Plateau in Chile. Construction of ALMA began in 2008, and the array saw first light in 2011. Up to now the astronomers, engineers, and technicians working at the site have had to live in temporary containers located at the facility’s basecamp. They will be pleased to hear that this situation will soon be coming to an end, as construction of the new ALMA Residencia reaches its final stages. Once all of ALMA’s antennas were successfully installed on the plateau, work began on the Residencia in early 2015. Located at the Operations Support Facility (OSF) at an altitude of 3000 metres, it is around 30 kilometres away from and over 2000 metres lower than ALMA, which resides in the Andes mountains at an altitude of 5000 metres. The OSF serves as the main basecamp for ALMA, coordinating all of ...

7 November 2016: Astronomers spend their time gazing out into the Universe — and occasionally the Universe seems to peer right back! This image, a composite of data from the Atacama Large Millimeter/submillimeter Array (ALMA) and the NASA/ESA Hubble Space Telescope, shows a very rare cosmic sight: a pair of interacting galaxies that have taken on an ocular structure. As the name suggests, some types of grazing encounters between galaxies create shapes that resemble the human eye. While galaxy collisions of this type are not uncommon, only a few galaxies with eye-like, or ocular, structures have been observed. The paucity of these features is likely due to their very ephemeral nature — ocular structures like these tend to only last for several tens of millions of years, which is merely the blink of an eye in a galactic lifetime. These two galaxies are named IC 2163 (left) and NGC 2207 (right) — IC ...

31 October 2016: For the first time, astronomers have seen a dusty disc of material around a young star fragmenting into a multiple star system. This image comprises new observations from the Atacama Large Millimeter/submillimeter Array (ALMA), Chile, and reveals the process in action! Stars form in cosmic clouds of gas and dust, when the thin material in the clouds collapses gravitationally into denser cores that in turn draw additional material inward. The infalling material forms a rotating disc around the young star, and is slowly consumed. Eventually, the young star gathers enough mass to create the necessary temperatures and pressures at its centre to trigger nuclear fusion. Stars that have no companion — such as the Sun — are not as common as we once thought. In fact, almost half of the stars in our galaxy have at least one companion, and some are more sociable still! Previous studies have indicated that ...

24 October 2016: On 22 October 2016, ESO Headquarters in Garching, Germany, opened its doors to the public. In conjunction with other facilities based on the science campus in Garching, ESO invited visitors to experience first-hand its work as the world’s leading ground-based astronomy organisation. Before the doors had even opened at 11:00, people were waiting outside, eager to experience all the different activities available. In total, some 4300 people grabbed the chance to have their questions answered by experienced astronomers; see live experiments (like here where ESO staff Andreas Jost shares the joy of electronics); join guided tours through the headquarters; listen to talks about ongoing astronomical research; build their own comet; and even participate in live interviews with astronomers in the Chilean Atacama Desert. If you participated in the Open House Day 2016 and took pictures, we invite you to share them on the Your ESO Pictures Flickr group.

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 ...