Picture of the Week

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 ...

12 August 2019: Thanks to the dark and clear conditions at ESO’s La Silla Observatory in Chile, capturing stunning images of the Milky Way is relatively commonplace for visiting photographers. However, despite the favourable conditions, producing beautiful and detailed images such as this is not easy — as ESO Photo Ambassador Petr Horálek discovered when taking this unusual photograph of the La Silla Observatory main building, which hosts the hotel, the canteen and other facilities. Petr took 52 individual shots to assemble this composite, moving and rearranging various pieces of furniture and himself — the coffee-drinking stargazer featured in the image — as he did so. Petr worked into the early hours, with only the low light of the corridor to disturb him. However, just as he prepared for the final few shots, all the chefs arrived, turning on a plethora of bright lights and ruining the photo. Petr had to return before ...

5 August 2019: The telescope in this eye-catching picture is appropriately named VISTA, short for the Visible and Infrared Survey Telescope for Astronomy. The telescope is located at ESO’s Paranal Observatory in Chile, where the altitude and arid climate make for cloudless skies and excellent viewing conditions. Different phenomena in the Universe produce different kinds of light, only a tiny fraction of which is visible to the human eye. VISTA observes infrared light, the same radiation that we can feel as heat. The three-tonne camera housed inside the telescope is extremely sensitive, allowing VISTA to detect this kind of light from very distant sources in the Universe and to produce both stunning images and groundbreaking scientific results. Enjoying the same exceptional skies as VISTA is another of ESO’s facilities, the Very Large Telescope (VLT), which can be just about be seen atop a distant peak. Despite the impressive size and ingenuity of these ...

29 July 2019: This spectacular portrait of the Centaurus A galaxy was captured under clear skies by the newest operational ESO observatory, SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars), located at the Paranal Observatory in Chile. The state of the art observatory is fitted an array of four one-metre telescopes, each named after one of the four Galilean moons. The SPECULOOS telescopes are neighbours of two of ESO’s most powerful telescopes, the Very Large Telescope (VLT) and VISTA. SPECULOOS is set to survey up to ten times more red dwarf stars than the TRAPPIST telescope (located at ESO La Silla Observatory) currently does. It is predicted statistically that it will then find at least twelve solar systems of a similar size to the now famous TRAPPIST-1 system. The Centaurus A galaxy (NGC 5128) is one of the brightest galaxies in the southern hemisphere night sky, located in the constellation of Centaurus. It ...

22 July 2019: The modern building in this image is the Residencia at ESO's Paranal Observatory in Chile, a home from home for the many professionals and technicians working at the observatory. Above the astronomers’ home in the Atacama Desert, the image shows the Milky Way galaxy — our home in the Universe. The Residencia was designed by the German architects Auer+Weber, and integrates perfectly into the arid landscape of the Atacama Desert in order to disturb astronomical observations as little as possible. The sandy colour and modern design of the building suit the Mars-like terrain around the observatory. The Residencia was chosen as the perfect hide-out for the Bond villain in the movie Quantum of Solace, and was blown up — only virtually — in one of the key scenes. Paranal Observatory hosts ESO's Very Large Telescope (VLT), as well as four Auxiliary Telescopes that can work together to form the Very ...

15 July 2019: This is SS 433, a microquasar first discovered forty years ago and located about 18 000 light-years away in the constellation of Aquila (The Eagle). This image, captured for the very first time at submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA), is special because it shows the jets emitted by a hot, swirling disc of material encircling the black hole at SS 433’s centre. Owing to its relative proximity, SS 433 is a particularly useful object for researchers looking to learn more about microquasars and the jets they emit. The corkscrew shape visible here is created by a phenomenon known as precession; as they move outwards through space, these two jets are slowly tumbling around an axis in a similar way to the motion of a gyroscope or a spinning top slowing down, the orientation of their rotational axes changing as they do so. The scale of this ...

8 July 2019: This red-hued cloud of gas is named Abell 24, and is located in the constellation of Canis Minor (The Lesser Dog). It is something known as a planetary nebula — a burst of gas and dust created when a star dies and throws its outer layers into space. Despite the name, planetary nebulae have nothing to do with planets. The term was coined by William Herschel, who also famously discovered Uranus; in a time of low-resolution astronomy, these nebulous objects appeared to resemble giant planets swimming in a dark cosmos. A Sun-like star spends most of its life converting hydrogen into helium in its core. In its twilight years the star runs out of fuel and becomes unbalanced; it can no longer resist the inward crush of gravity and the core begins to collapse. The temperature in the core rises dramatically while the cooler outer layers expand, causing the entire ...

1 July 2019: Almost exactly 100 years ago, a remarkable event occurred: a total solar eclipse. This eclipse was special in more ways than one. Firstly, at just under seven minutes in duration, it was the longest such eclipse in over 500 years. Secondly, it was used by astronomers to explore the then-new theory of general relativity — with successful and groundbreaking results. Einstein published his general theory of relativity in 1915. The total solar eclipse of 1919 offered the perfect opportunity to test it experimentally, by exploring whether — and how — the immense gravity of the Sun bends and distorts incoming light from more distant stars, as predicted by Einstein’s theory. For a brief moment during the eclipse, the Moon would block the Sun’s light in the sky and make visible some of the stars that lie close to the line of sight of the Sun, not normally visible during the ...

24 June 2019: ESO’s observatories located on the mountains of Chile — La Silla, Paranal and Chajnantor Plateau — are home to a wide range of telescopes built and operated by the organisation’s 16 Member States. As time passes, older telescopes are slowly overtaken by their newer and more advanced peers. One of these old-timers is pictured here: the Swedish-ESO Submillimetre Telescope (SEST). Built back in 1987 at La Silla, the SEST was a groundbreaking instrument. It was the only large telescope in the southern hemisphere to study radio waves from objects in the distant Universe (known as submillimetre astronomy). A huge dish, with a diameter of 15 metres, the telescope was able to observe some of the most extreme phenomena in the cosmos. Eventually, however, newer and more advanced telescopes — such as the Atacama Large Millimeter/submillimeter Array (ALMA) and Atacama Pathfinder Experiment (APEX), both situated on Chajnantor Plateau — began to ...

17 June 2019: This stunning photograph shows some of the antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA), all observing a panoramic view of the Milky Way’s centre. There is far more to ALMA than shown here; the array can span distances of up to 16 kilometres and is formed of 66 individual antennas! Some features visible in the sky include Crux (The Southern Cross) just above and to the right of the nearest antenna, and the Carina Nebula slightly further to the right. Astronomers use ALMA to peer into gigantic star-forming molecular clouds, and to observe galaxies forming at the very edge of the observable Universe. The green lights visible on the telescopes are a normal part of their operation, but in this scene they also cast an ethereal, otherworldly glow over the Chilean site. This photograph was taken by Petr Horálek, one of our ESO Photo Ambassadors.

10 June 2019: This rugged, wrinkled landscape may resemble Mars, but it is in fact much closer to home — this patch of rippled terrain is a northern region of the Chilean Atacama Desert, home to many of ESO’s world-leading telescopes and observatories. The distinctly otherworldly appearance of the desert has not gone unnoticed; this part of the world is actually used as an “analogue site” for Mars! Scientists visit the Atacama to explore: soil composition and texture; potential similarities in surface geology and features; limitations for past biological activity (including whether such locations may, or may once have been, friendly to extremophile life); weather conditions; aridity and more. Perhaps most importantly, sites like the Atacama can help us to prepare for both in-progress and planned space missions (manned and unmanned alike) by providing a suitable environment in which to test equipment, manoeuvres, and mission plans. Visible just below right of centre in ...

3 June 2019: This stunning long-exposure photograph by ESO Photo Ambassador Petr Horálek captures the hive of activity that is ESO’s La Silla Observatory, the distant glow of roads and settlements in the Chilean Atacama Desert, and the unmissable faint green radiance of airglow (produced by light in Earth’s upper atmosphere). Flirting with the horizon, the mythical Seven Sisters of the Pleiades open star cluster can be seen dancing above distant mountain peaks. Directly above them, the dazzling constellation of Orion (The Hunter) dominates the view, as giant clouds and arcs of ionised gas — called emission nebulae, and seen here as red patches — encompass the imagined form of mythological hunter. The familiar sight of the Milky Way is also visible, carving its way across the night sky. The La Silla Observatory is located in northern Chile at an altitude of 2400 metres. It enjoys some of the darkest night skies on ...

27 May 2019: Even in their downtime, many astronomers cannot resist catching one more glimpse of the star-studded sky. This image captures a fascinated astronomer stargazing from the Residencia, ESO’s living quarters for staff working at Paranal Observatory in Chile. This view shows the dusty and star-filled band of the Milky Way rising over the Atacama Desert, the remote home of ESO’s Very Large Telescope (which sits atop Cerro Paranal). The desert’s inhospitable conditions drove the construction of the Residencia, which was completed in 2002. An oasis for astronomers, the building contains 108 bedrooms built into a depression in the desert, and is considered a refuge from the harsh conditions of the Atacama — it even hosts a verdant garden and swimming pool! The building was designed to blend into its environment, and to minimise light pollution in the exceptionally dark skies of Paranal. The Residencia’s fascinating and unusual setting captured the eye ...

20 May 2019: In a once-in-a-lifetime opportunity, staff at ESO’s Paranal Observatory were treated to a unique performance by the world-renowned cellist Yo-Yo Ma. On 1 May 2019, the celebrated musician visited Paranal to see the astronomical centre, home of the Very Large Telescope (VLT), and experience its dazzling skies first-hand. To the delight of the staff, he gave a special concert for which he requested completely dark skies. He is pictured here during the starlit performance, with the majestic band of the Milky Way and the Magellanic clouds overhead, making for a uniquely atmospheric setting. He gave renditions of several Bach cello suites among other pieces, and even asked his audience if they had any special requests. The next day, Yo-Yo Ma met with some members of staff, who shared their experiences of working in the extreme environment of the Atacama Desert to unveil the mysteries of the Universe. He was given ...

13 May 2019: The constellation of Orion (The Hunter) is one of the most recognisable collections of stars in the night sky. We have noted Orion’s prominent stars for tens of thousands of years at least, and likely far longer. Chinese astronomers called it 参宿 or Shēn, literally “three stars”, for its three bright dots (which form the Hunter’s belt). The ancient Egyptians regarded it as the gods Sah and Sopdet, manifestations of Osiris and Isis, respectively, whereas Greek astronomers saw a brave hunter — the eponymous Orion — with his sword above his head, ready to strike. Mythology aside, Orion is a fascinating patch of sky. This image, from ESO's Very Large Telescope, shows a reflection nebula nestled at the heart of the constellation — NGC 2023. Located close to the well-known Horsehead and Flame Nebulae, NGC 2023 lurks about 1500 light-years away from Earth, and is one of the largest reflection ...

6 May 2019: This striking UHD panorama shows a bizarre-looking scene at ESO’s Paranal Observatory, home to ESO’s Very Large Telescope (VLT). The Milky Way graces the skies above the observing site every single night, and is visible in stunning detail and clarity. But here, the galaxy appears to dip down through the night sky and create two separate columns, while still filling the sky towards the top of the frame. Why is this view so distorted? The sculpting and reshaping of this familiar celestial scene result from the way in which the photographer, ESO Photo Ambassador Petr Horálek, captured the image. Horálek photographed the entire dome of the sky, from zenith to horizon, a full 360 degrees around. The “two Milky Ways” are in fact a single band — the plane of our galaxy as it arcs across the sky from horizon to horizon. As it passes overhead, it appears to spread ...

29 April 2019: This is one of 74 nearby galaxies whose stellar nurseries were recently observed by the Atacama Large Millimeter/submillimeter Array, or ALMA, in an astronomical census called Physics at High Angular resolution in Nearby GalaxieS (PHANGS). So far, around 100 000 of these stellar nurseries have been imaged in over 750 hours of observation. ALMA’s remarkable sensitivity provides data at high enough resolution to study these regions in detail, and shows that some are bursting with new stars, while others evolve more gradually. This anticipated diversity in the process of how stars form was the motivation behind this enormous effort. There have long been theories that aimed to explain how and why these differences might occur, some involving the characteristics of the home galaxy itself — properties such as size, age, and internal dynamics — but our lack of high-resolution data had been an obstacle to testing them. The vast quantity ...