Picture of the Week 2018

31 December 2018: This panorama of the landscape around ESO’s Paranal Observatory, located in the Chilean Atacama Desert, was taken by ESO Photo Ambassador Petr Horálek. Captured at dusk, it shows the moment just after sunset, when the the sky is painted in beautiful colours of yellow, orange, red, even blue-purple, and the reddish hues of the desert below are enhanced by the soft light. This time of day is known as twilight, but is also referred to as the blue hour (named for the colour of the sky). The unique and ethereal quality of the light during blue hour has also earned it the nickname of “sweet light” amongst artists and photographers. The planet Venus stands out against the pink of the sky in the very centre of the image, while the Very Large Telescope (VLT) rests atop the mountain on the right, Cerro Paranal. The Andromeda Galaxy is faintly visible to ...

24 December 2018: Few people have ever viewed the Moon through a telescope as monumental as ESO’s Very Large Telescope (VLT). Astronomers at Paranal Observatory in Chile recently enjoyed this unique opportunity when one of the telescope’s instruments, VIMOS (VIsible Multi-Object Spectrograph), was decommissioned to free up a space at the UT3 telescope for the upcoming CRIRES+ (the CRyogenic InfraRed Echelle Spectrograph Upgrade Project). VIMOS was astonishingly productive; the spectrograph studied thousands of distant galaxies seen at a time when the Universe was only at a third of its current age, and mapped their distribution and physical properties. The sensitive instruments used by the VLT, including VIMOS, are designed to image dim objects billions of light-years away, and therefore objects as near and bright as our planet’s moon easily completely saturate them with far too much light. But when VIMOS was decommissioned after 16 years of service, the astronomers stationed at Paranal took ...

17 December 2018: As 2018 draws to a close we send you all our very best wishes! On behalf of everyone at the European Southern Observatory, have a very merry end of the year and a fruitful start to 2019.

10 December 2018: The R Aquarii system is a symbiotic binary star surrounded by a large, dynamic nebula. Such binaries contain two stars in an unequal and complex relationship — a white dwarf and a red giant. In a disquieting act of stellar cannibalism, the white dwarf is stripping matter from its larger companion. The tormented red giant and the unstable white dwarf occasionally eject matter in weird spurts, loops and trails — forming the curious shapes seen in these images. In this unusual comparison image — a rare case of dynamic evolution captured with ground-based telescopes — we see the difference 15 years can make. It may be the mere blink of an eye on a cosmic timescale, but it provides us with a wonderful opportunity to observe a truly dynamic system as it changes shape in our skies. These images show the evolution not only of R Aquarii, but also of ...

3 December 2018: This spectacular Picture of the Week was produced from data gathered by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, combined with data from the NASA/ESA Hubble Space Telescope. It shows a cluster of stars named Westerlund 1, one of the most massive young star clusters known to reside in the Milky Way. Excitingly, it also shows the comet-like “tails” of material stretching away from some of the giant stars in Westerlund 1. Such tails are formed in the thick, relentless winds that pour from the cluster’s stellar residents, carrying material outwards. This phenomenon is similar to how comets get their famous and beautiful tails. Comet tails in the Solar System are driven away from the nucleus of their parent comet by a wind of particles that streams out from the Sun. Consequently comet tails always point away from our Sun. Similarly, the tails of the huge red stars shown ...

26 November 2018: This photo shows the future site of the Technical Facility for ESO’s Extremely Large Telescope (ELT) — and construction is well underway! Situated at ESO’s Paranal Observatory in the Chilean Atacama Desert, this facility will be the maintenance hub for the ELT, which will take up residence on Cerro Armazones. Behind the site, ESO’s Very Large Telescope (VLT) can be seen standing high up on Cerro Paranal. The ELT’s 39-metre primary mirror will be made up of 798 hexagonal segments, and will be controlled by a system of very-high-precision sensors. This technology, known as active optics, will allow the telescope to continually adjust each individual segment to account for disturbances such as temperature, gravity and pressure due to wind, in order to maintain the perfect shape to enable optimal observations. To maintain tip-top quality, this colossal mirror must undergo a regular process of stripping, washing, and recoating. Since each individual ...

19 November 2018: This colourful image shows a part of the Rosette Nebula in the constellation of Monoceros (The Unicorn). It is an emission nebula, composed of clouds of gas that are made to glow by the radiation emanating from stars within. The Rosette Nebula is a fairly typical example of an emission nebula — but typical does not mean boring! Nebulae are some of the most beautiful celestial objects out there, and they frequently show up spectacularly in images taken by astronomical telescopes, as seen here. In nebulae such as this, gas and dust are combining to produce a new generation of stars. Initially these newly-formed stars are shrouded in the dusty clouds that gave them birth, and cannot be seen in visible light. But after a while they blow away the denser material and their powerful radiation pours out to ionise the surrounding gas, causing it to glow brightly. These elements ...

12 November 2018: ESO's Very Large Telescope (VLT) has captured an unprecedented series of images showing the passage of the exoplanet Beta Pictoris b around its parent star. This young massive exoplanet was initially discovered in 2008 using the NACO instrument at the VLT. The same science team since tracked the exoplanet from late 2014 until late 2016, using the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) — another instrument on the VLT. Beta Pictoris b then passed so close to the halo of the star that no instrument could resolve them from one another. Almost two years later, after seeming to merge into the image of the star, Beta Pictoris b has now emerged from the halo. This reappearance was captured again by SPHERE. The complete series of images, with the bright glow of the star Beta Pictoris blocked out, have been compiled to create a stunning and unique time-lapse of the long-period ...

5 November 2018: This once-busy eye on the sky now gazes wistfully into the heavens from its mountaintop home. Located at ESO’s La Silla Observatory in Chile’s Atacama Desert, this is the dish of the now-retired Swedish-ESO Submillimetre Telescope (or SEST for short). The SEST was decommissioned in 2003 to make way for the Atacama Pathfinder Experiment telescope (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA), both of which sit on the Chajnantor plateau in Chile’s Atacama region (as their names suggest). In its day, the SEST was the largest sub-millimetre telescope in the southern hemisphere; it notably broke new ground in the study of some of the coldest regions in the Milky Way, where stars are just beginning to form from cosmic gas and dust. The bright streak of the Milky Way rises above the SEST in this image. Within this river of light one can, poetically, see some of the huge ...

29 October 2018: The era of extremely large telescopes is beginning — and it will revolutionise our understanding of the Universe. ESO’s Extremely Large Telescope (ELT) is currently under construction in the remote Chilean Atacama Desert; this groundbreaking telescope alone will collect more light than over 200 NASA/ESA Hubble Space Telescopes. As the name suggests, such telescopes are truly colossal. The largest primary mirrors — by which a telescope collects light — currently in operation at all of ESO’s sites are the 8.2-metre-diameter mirrors in the four Unit Telescopes comprising the Very Large Telescope (VLT). The ELT will dwarf the already impressive VLT with its vast mirror at 39 metres in diameter! However, constructing a single, science-quality mirror of such a size is simply not possible — the ELT’s primary mirror will, in fact, be a complex honeycomb arrangement of 798 tessellated hexagonal 1.4-metre mirrors. Finding a suitable place for such a structure ...

22 October 2018: This image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows the area surrounding Sagittarius A*, the supermassive black hole that lurks at the centre of the Milky Way — highlighted here with a small circle. New research has revealed exciting evidence of interstellar gas and dust orbiting the black hole at high speeds. The molecular-hydrogen-rich gas clouds which have been identified are known as molecular cloudlets, and they have never before been unambiguously detected. This image actually shows the distribution of molecules including carbon monoxide, the cloudlets’ second most abundant molecular component. The cloudlets lie 26 000 light-years away from us, orbiting fast and relatively close to the black hole, at a distance of about one light year. ALMA’s high resolution allowed scientists to detect the cloudlets, which are the products of pre-existing massive clouds rotating around the centre of our galaxy. These clouds were tidally disrupted into dense fragments ...

15 October 2018: On Saturday 13 October 2018, ESO’s Headquarters in Garching, Germany, opened its doors for ESO’s yearly Open House Day. Along with other institutes 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. This year’s Open House Day also included events at the ESO Supernova Planetarium & Visitor Centre, which opened in April this year. Attendees waited impatiently for the doors to open at 11:00, eager to experience all the different activities on offer. 5200 people took the opportunity to have their questions answered by experienced astronomers and to peer behind the scenes of an organisation at the forefront of astronomical research. The programme included live experiments, guided tours, an exhibition of ESO’s multiple observatories, talks from ESO scientists, and a live connection to ESO’s sites in Chile. If you participated in the Open House Day 2018 and ...

8 October 2018: This object is possibly the oldest of its kind ever catalogued: the hourglass-shaped remnant named CK Vulpeculae. Originally thought to be a nova, classifying this unusually shaped object correctly has proven challenging over the years. A number of possible explanations for its origins have been considered and discarded. It is now thought to be the result of two stars colliding — although there is still debate about what type of stars they were. CK Vulpeculae was first spotted on 20 June 1670 by French monk and astronomer Père Dom Anthelme. When it first appeared it was easily visible with the naked eye; over the subsequent two years the flare varied in brightness and disappeared and reappeared twice, before finally vanishing from view for good. During the twentieth century, astronomers came to understand that most novae could be explained by the runaway explosive behaviour and interactions between two close stars in ...

1 October 2018: Autumn has arrived, and the colours of the temperate Northern Hemisphere are slowly changing. This photo, taken by ESO Photo Ambassador‌ ​Petr Horálek, shows the two main buildings of ESO’s Headquarters in Garching, Germany, surrounded by the wondrous golden hues that announce the beginning of the season. Not all parts of the globe experience autumn; the tropics experience few changes in sunlight through the year, and polar regions lack a transitory season between summer and winter. Only northern and southern temperate regions have the chance to observe abscission, the annual shedding of leaves, for a few months each year (starting in September and March respectively). But why do tree leaves change their colours? Rather than attempting to endure the limited light levels and cold temperatures that accompany the autumnal and wintry months, so-called deciduous plants prefer to rest — and autumn represents the seasonal preparation for this period of dormancy. ...

24 September 2018: Chile’s Atacama Desert comprises over 100 000 square kilometres of arid, barren terrain. However, for astronomers working at the largest ground-based astronomical project in existence, the Atacama Large Millimeter/submillimeter Array (ALMA), some of the most important measurements occur on the scale of just a few millimetres. The ALMA Operations Support Facility (OSF) sits at an altitude of 2900 metres above sea level in the Andes. From here, astronomers, technicians, and engineers can control each of ALMA’s individual 66 antennas, which are located over 2000 metres higher, at 5000 metres elevation, up on the Chajnantor plateau. Getting the antennas up to this plateau presents quite an engineering challenge. Enter Otto and Lore! These huge orange beasts — one of which is seen here — were specifically designed and built in Germany to carry the 100-tonne antennas from the OSF to Chajnantor (a distance of some 28 kilometres). When they arrive, the ...

17 September 2018: This image shows a dwarf galaxy in the southern constellation of Phoenix named, for obvious reasons, the Phoenix Dwarf. The Phoenix Dwarf is unique in that it cannot be classified according to the usual scheme for dwarf galaxies; while its shape would label it as a spheroidal dwarf galaxy — which do not contain enough gas to form new stars — studies have shown the galaxy to have an associated cloud of gas nearby, hinting at recent star formation, and a population of young stars. The gas cloud does not lie within the galaxy itself, but is still gravitationally bound to it — meaning that it will eventually fall back into the galaxy over time. Since the cloud is close by, it’s likely that the process that flung it outwards it is still ongoing. After studying the shape of the gas cloud, astronomers suspect the most likely cause of the ...

10 September 2018: From the 5 to 19 August this year, AstroCamp 2018 took place at the Centre for Environmental Education and Interpretation of the Corno de Bico Protected Landscape in northern Portugal. AstroCamp is an astronomy-focused summer academic program for secondary students, which aims to bring together students who have different backgrounds and life experiences, but a common passion: astronomy. Over the course of two weeks, the students — astronomy enthusiasts aged between 15 and 18 from various European Union countries — attended lectures, had Skype conversations with researchers in different countries, worked on a computational project with data from some of the world’s best telescopes, and took part in night-time astronomical observation sessions. Social activities such as hiking, sports, community service activities and film and documentary sessions also contributed to making the camp a fun and enriching experience. While this camp has been running since 2012, it was only opened up ...

3 September 2018: ESO’s La Silla Observatory, situated in northern Chile, offers the resident telescopes unrivalled views of both the cosmos and the region’s barren, but beautiful landscape. Photographed by Alberto Ghizzi Panizza from the ramp leading to ESO’s New Technology Telescope (NTT), this view captures La Silla under the magnificence of the Milky Way, which unmistakably carves its way across the night sky overhead. Sitting proudly at the centre of the frame is the ESO 3.6-metre telescope, host of the planet-hunting HARPS instrument. Below sits the small grey and white enclosure (nicknamed the sarcofago, or sarcophagus) of the Télescope à Action Rapide pour les Objets Transitoires (TAROT). To the far right, the silver-sheened back of the decommissioned 15-metre Swedish-ESO Submillimetre Telescope (SEST) can be seen atop an isolated peak, and, finally, to the left of the road in the foreground sits the corrugated paneling and white dome of the Swiss 1.2-metre Leonhard ...

27 August 2018: This Picture of the Week shows a huge celestial “V” emblazoned across the night sky over ESO’s Paranal Observatory, which is situated atop Cerro Paranal in Chile. One arm of the “V” is noticeably clearer than the other; the right arm, pointing towards the top right corner of the frame, is traced out by the beautiful star-studded centre of the Milky Way. The fainter arm, leaning leftwards, is formed of glowing columns of diffuse zodiacal light, a phenomenon caused by incoming sunlight that is scattered by small particles of cosmic dust. While we often see both the Milky Way and zodiacal light at Paranal thanks to the site’s famously clear skies, the “V” alignment shown here is unusual. Zodiacal light is related to the Earth’s path through space, as the dust particles responsible for scattering the sunlight are all within a cloud that lies on the ecliptic plane (dubbed the ...

20 August 2018: In this spectacular image, taken by ESO Photo Ambassador Petr Horálek, we see the bright arc of the Milky Way stretching across the sky above ESO’s La Silla Observatory in Chile. On the ground are the dome of ESO’s 3.6-metre optical telescope (on the right) and the silvery dish of the Swedish-ESO submillimetre telescope (on the left). Even though it was decommissioned in 2003 to make way for the more advanced APEX and ALMA instruments, the Swedish-ESO dish still seems to be gazing longingly at the sky, perhaps hoping for another chance to explore the mysteries of the heavens. The Milky Way dominates this image, showing clearly why La Silla is one of the best astronomical sites in the world, famed for its dark skies and clear air. From the peak of the bright arc hangs a striking red feature known as Gum Nebula. This, like similar regions along the ...