Picture of the Week 2020

28 December 2020: The wonders of the cosmos have inspired awe since the dawn of time. Thousands of years ago, ancient civilisations observed celestial objects to mark the seasons and time, to weave myths and stories, and to make sense of the cosmos around them — and modern-day stargazers are captivated by the beauty and mystery of the night sky in the very same way. We have been turning camera lenses to the skies since the emergence of early forms of photography, hoping to capture the spectacle of a dark sky dotted with myriad pinpricks of light. But it wasn’t until 1850 that the first star was captured on camera. The following decades saw the development of increasingly complex camera equipment, and images of celestial objects and phenomena created using light from across the electromagnetic spectrum have since become the cornerstone of modern astronomy. This beautiful photograph of the glimmering arch of the ...

21 December 2020: As the unconventional year of 2020 draws to a close, we send you and all of your families our very best wishes! Undoubtedly this year has been challenging for many, and here at ESO we have worked to adapt to these unprecedented times. After a pause of a few months, we have restarted limited science operations at our observatories in Chile, under strict safety measures. As our telescopes and instruments resume their observations of the night sky, we continue to be inspired by the Universe’s wonders and look forward to sharing more fascinating astronomical discoveries with you all. On behalf of everyone at the European Southern Observatory, we hope you have a very safe and healthy end of the year and a brilliant start to 2021!

14 December 2020: The antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, appear to emit an eerie, vivid shade of green light in this Picture of the Week. Situated high up on the isolated Chajnantor plateau in Chile’s Atacama Desert, ALMA seems like the perfect place for friendly extraterrestrials to discreetly land and make contact…but something far more mundane is responsible for this otherworldly green glow. The light emanates from indicator lights, which show whether or not it is safe for staff to approach the antennas. A green light as pictured indicates that it’s safe to approach. An alien world is, however, visible above the antennas. In the top left of the image, in the clear Chilean sky, two bright stars can be seen next to each other within the band of the Milky Way. These stars are often called The Pointers, as they “point” towards the ...

7 December 2020: This photograph, taken by ESO Photo Ambassador Petr Horálek, looks west from ESO’s Paranal Observatory in Chile. The bright object at the centre of the frame is the Moon — slightly to its upper left is the ringed planet Saturn, while rocky Mercury sits to the lower left. Saturn and Mercury in conjunction can be difficult to see with the naked eye from some latitudes, but this breathtaking image captures them beautifully, despite the relatively bright light from the nearby Moon. The dusty Milky Way appears to split the sky horizontally, with a star-studded night view above and the last signs of the Sun lingering below. Many famous nebulae are visible across this cosmic curtain, such as the Lagoon Nebula, Cat’s Paw Nebula, and Trifid Nebula. The individual telescopes in this image together make up ESO’s Very Large Telescope (VLT), the world’s most advanced optical and infrared observatory. The VLT ...

30 November 2020: Resembling a river of light flowing through the dry, otherworldly landscape of northern Chile, the road to ESO’s Paranal Observatory is a lifeline for the facility. Sited in one of the most remote locations in the world to benefit from the extremely low light pollution there, the observatory can only be accessed by this road, which winds its solitary way through the calm, barren terrain. Atop the distant mountain, called Cerro Paranal, it is possible to see the tiny shapes of the VLT Survey Telescope, and all four of the Unit Telescopes (UTs) that make up ESO’s Very Large Telescope. Though small in this Picture of the Week, up close these telescopes are veritable behemoths — each UT mirror alone spans over eight metres! This photo was taken from the vantage point of another of ESO’s facilities, the VISTA telescope, on an adjacent peak in the Atacama Desert, ...

23 November 2020: The thousands of newly formed stars at the heart of NGC 5236 were imaged with the MUSE instrument, attached to ESO’s Very Large Telescope at Paranal Observatory in Chile. Referred to mostly as the Southern Pinwheel galaxy, NGC 5236 receives its common name from its beautiful spiral arm configuration and its location in a Southern Hemisphere constellation: Hydra. Bright regions of star formation light up this galaxy, including the region imaged here, located within the galaxy's centre. With the right conditions, and commonly within the spiral arms of a galaxy, cold molecular clouds mostly composed of hydrogen gas can collapse and form into brand new stars. In larger clouds, the burning of a new star can create a domino effect, initiating the collapse of the surrounding gas into even more stars. Within a galaxy’s centre however, other processes are at play. The supermassive black hole at the centre of NGC ...

16 November 2020: To the right of this image captured in northern Chile, the eye-catching arc of the Milky Way soars above the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. But despite the breathtaking view, the glow of our home galaxy is here rivalled by another type of interesting light. The image also shows, on the arc to the left, a faint brightening of the night sky in the region of the ecliptic directly opposite the Sun. This phenomenon is known as gegenschein (German for “countershine”) and is created as interplanetary dust in the outer part of the Solar System — from comets and broken-up asteroids — scatters incoming sunlight. In most parts of the world, phenomena such as gegenschein, or the stunning arc of the Milky Way, are masked by light pollution from artificial light sources. Some estimates indicate that over 80% of the world’s population lives under ...

9 November 2020: At first glance, this image looks both awesome and intimidating, with the enormous beams of light resembling some terrible cosmic weapon. Fortunately, that is not the case! This ESO Picture of the Week shows something far more benign — a mixture of gas, dust, and powerful lasers. Among the largest nebulae in the southern night sky, the Carina Nebula is a perfect viewing target for ESO’s Very Large Telescope (VLT). In this image, the nebula appears as a stunning pink cloud in the clear sky above ESO’s Paranal Observatory in Chile, home of the VLT. The Carina Nebula is a vast cloud of dust and gas — this gas is ionised and made to glow by the stars within the nebula itself. The cutting-edge Adaptive Optics Facility installed on one of the 8.2-metre Unit Telescopes (UTs) of the VLT is in full operation here. The orange laser beams are sent ...

2 November 2020: The otherworldliness of this image, obtained at ESO’s Very Large Telescope (VLT) in northern Chile, is due to a combination of natural and artificial light phenomena. This ethereal image captures a lunar halo on rare cloudy skies over ESO’s Paranal Observatory. This optical phenomenon is created when moonlight is refracted by millions of small ice crystals and water droplets in the surrounding atmosphere. These haloes are reasonably common; however, they require quite a bit of light to appear, so the Moon must be in a specific position relative to the Earth and the Sun to reflect enough light to produce a fine ring like this one. This particular halo comprises multiple coloured bands that are formed in the same way as in a rainbow — light of different wavelengths is refracted by varying amounts. White light is thus broken into its constituent parts, dispersing to create a spectrum of ...

26 October 2020: ESO’s New Technology Telescope (NTT) has captured the familiar sight of three of our planetary neighbours as limited science operations restart at La Silla Observatory, located in the Chilean Atacama desert. Images of the three brightest planets visible in the sky that night: Jupiter, Mars and Saturn were taken as the operations team tested the NTT’s versatile EFOSC2 instrument. The subtle orange, yellow and reddish hues of the three planets are seen by combining images captured by the instrument using five different filters. This Picture of the Week shows a montage of the images taken of the three planets. The relative sizes seen in this montage are proportional to the angular size of the planets in the sky. Mars appears rather large and bright because it was in opposition when the image was taken, that is, the Earth was positioned between Mars and the Sun. Following these successful tests, very ...

19 October 2020: Winter nights on the Chajnantor Plateau can seem incredibly isolating — but the wonder of some of the driest, darkest skies in the world is definitely something to be shared. This image shows two of the 66 antennas that comprise the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, as they work together to observe the skies in millimetre and submillimetre wavelengths. These wavelengths are notoriously difficult to observe, as water vapour in the atmosphere absorbs this kind of light and prevents it from reaching the ground. To catch sight of it, telescopes must be placed at very high altitudes where the air is drier and less absorbent. For ALMA, that means an elevation of 5000 metres. Hanging above the pair of telescopes is the constellation of Orion (The Hunter), identifiable by his distinctive star-studded belt. His shoulder is marked by the red supergiant Betelgeuse, on the ...

12 October 2020: In this eye-catching Picture of the Week, bright star trails fill the sky above ESO’s La Silla Observatory in Chile. Such trails are formed by the Earth spinning on its axis — our planet’s rotation causes the stars to seemingly move through the sky, slowly tracing out perfect concentric arcs and circles as they do so. A photograph like this therefore requires a long exposure to capture the passage of time. At the centre of this image is the decommissioned Swedish-ESO Submillimetre Telescope , and the ESO 3.6-metre telescope sits atop the mountain to the left, aglow with activity. This telescope hosts HARPS (the High Accuracy Radial velocity Planet Searcher), which searches for exoplanets by measuring the tiny “wobbling” motions of their host stars as the planets sweep around in their orbits.

5 October 2020: Images such as this one really highlight the movement of our planet through space. As well as travelling on an elliptical path around the Sun, the Earth spins on its axis — and it is this rotational motion that’s responsible for this eye-catching view. As the Earth rotates, the stars above appear to change position and move through the sky on long arches, creating these eye-catching star trails centred on the south celestial pole. To successfully capture the apparent motion of the stars, photographer Fred Kamphues took multiple long-exposure shots and stacked them together, creating this remarkable photograph. The illuminated road below leads up to Paranal Observatory, home to ESO’s Very Large Telescope (VLT). In this image, two of the four main Unit Telescopes (UTs) and the VST can be seen atop the mountain (Cerro Paranal). It is the laser beams from one of these UTs, emphasised by ...

28 September 2020: Despite its name, ESO’s Very Large Telescope, the VLT, is not a single telescope! It is in fact made up of an array of four 8.2-metre-diameter Unit Telescopes (UTs) (one of which is shown here) and four additional, movable, 1.8-metre-diameter Auxiliary Telescopes (ATs) (three of which are visible on the right side of this image). Each UT has its own individual name in the Mapuche (Mapudungun) language. The star of this image is Antu (or UT1, the first of the UTs), and is pictured here sitting atop Cerro Paranal in Chile. This polychromatic image, taken by ESO Photo Ambassador Petr Horálek, also captures the beautiful colours of the cloudy night sky encircling Antu. Many night-sky objects are visible here. Starting from the left we see the pink California Nebula, the Pleiades star cluster, the fiery river of the Milky Way, the constellation of Orion and its famous Belt, the looping ...

21 September 2020: The ongoing large-scale ATOMIUM project is being conducted in collaboration with ALMA, the Atacama Large Millimeter/submillimeter Array, which is located in Chile and has ESO as a partner.The project set out to map the stellar winds blowing out from around a dozen red giant stars, an ambitious goal made possible thanks to ALMA’s spectacular resolution. These stellar winds — which are sometimes millions of times stronger than those of our Sun — were expected to be spherical, like the parent stars that they are blasted away from. However, researchers did not observe spherical stellar winds, but something quite different. As seen in the above image — which shows winds around a star called R Aquilae — the team found that in all cases the stellar winds were not spherical, but had different shapes, including some resembling the delicate petals of a rose. The patterns seen in the stellar winds have ...

14 September 2020: Despite its name, ESO’s Very Large Telescope (VLT) is not a single telescope. It is actually made up of four separate 8.2-metre Unit Telescopes — the larger structures visible here — and four movable 1.8-metre Auxiliary Telescopes, two of which can be seen to the back left of this image. Unit Telescope 4 is equipped with laser guide stars, which beam upwards and lights up the atmosphere some 90 kilometres above ground. These bright laser beams reach high into the mesosphere, where they excite sodium atoms and cause them to emit photons, creating a bright artificial star, which can be used for adaptive optics correction. Settled on a mountain peak in the remote Atacama Desert, the VLT experiences little or no light pollution. However, the exquisite sky isn’t completely dark. This picture shows the beautiful, diffuse glow of sunlight being scattered by interplanetary dust — zodiacal light — while the ...

7 September 2020: The Milky Way displays its stunning shape and colours as it arches over the Chilean desert. It creates the perfect frame for the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA). Two of the Milky Way’s satellite galaxies can also be seen, the Large and Small Magellanic Clouds appearing in the crystal-clear sky as smudges beneath the arc of their larger neighbour. The artificial green glow which illuminates the ALMA antennas provides a striking contrast to nature’s stunning visual display above. ALMA is situated more than 5000 metres above sea level in the Chilean Desert. Here the dry air and thin atmosphere allow a spectacular view into the Universe and make it the perfect place for a sensitive telescope like ALMA. Rather than being one single telescope, ALMA is composed of 66 separate, movable antennas spread over the Chajnantor plateau. By using different configurations of the antennae, the resolution with ...

31 August 2020: This image shows a beautiful nighttime scene at ESO’s Paranal Observatory in Chile. The bright band of the Milky Way cuts prominently through the centre of the scene, crammed with bright gas, dark dust, and sparkling stars, seemingly diving downwards to meet the glowing horizon. The boxy structure of UT1 (Antu), one of the four Unit Telescopes comprising the ESO’s Very Large Telescope (VLT), can be seen at the centre of the frame, while a smaller Auxiliary Telescope is visible to the right, its dome wide open as it scans the skies. With its eight telescopes, four of which — the auxiliaries — are movable, the VLT can act as a highly sensitive interferometer — so sensitive, in fact, that it can distinguish between the two headlights of a car at the distance of the Moon! The beautiful and oft-photographed skies above the VLT are some of the clearest in ...

24 August 2020: The MUSE instrument on ESO’s Very Large Telescope (VLT) in Chile has observed NGC 1365, a double-barred spiral galaxy located about 56 million light-years away in the Fornax galaxy cluster, allowing us to construct this spectacular colour image. The galaxy is also known as the Great Barred Spiral Galaxy, after its two central bar-shaped structures, made up of stars. The two bars of NGC 1365 are a rare phenomenon and are thought to have originated by the combined effects of galaxy rotation and the complex dynamics of the stars. Its largest bar of stars, too large for its structure to be visible in this image, connects its outer spiral arms to its centre. What we can see is the much smaller second bar of stars, nestled within the main bar. It is likely this secondary bar acts independently of the main bar, rotating more rapidly than the rest of the ...

17 August 2020: Incredible splashes of colour — greens, reds, blues, and every colour in between — paint the night sky above ESO’s Paranal Observatory in Chile, illuminating the barren desert landscape below. The light from billions of stars, glowing nebulae, and other cosmic phenomena creates the giant arch of the Milky Way, which stretches across the sky and perfectly frames the Very Large Telescope (VLT) sitting atop the peak at the centre of the image (Cerro Paranal). This particular view was taken from the site of ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA). The winding road between VISTA and the VLT can be seen below, illuminated by faint yellow lights. These are, notably, the only human-made lights visible in the entire scene — Paranal staff take great care not to create unnecessary light pollution that may hinder the astronomical work at the world-class observing site. The Milky Way is not ...