Picture of the Week

4 July 2022: The Eta Aquariids meteor shower, which peaked in early May this year, was captured in this stunning image by astrophotographer Petr Horálek. It was taken near San Pedro de Atacama, a Chilean town about 50 km away from the Chajnantor observatory site, where APEX and ALMA, astronomical facilities co-owned by ESO, are located. The Eta Aquariids meteors are caused by leftover debris from Halley’s comet and make up the bright, arrow-like darts of light in the photo. But don’t stop there: this image is literally full to the brim of astronomical phenomena. The luminous object towards the bottom of the sky is Venus. Above it, arranged in a satisfying line, are several planets in conjunction. Directly above Venus is Jupiter, followed by the bright red Mars, and then Saturn. Conjunctions such as this are rare, often occurring decades apart. The planets also trace the zodiacal light, the faint glow stretching ...

25 April 2022: This image, taken at ESO’s La Silla Observatory in Chile’s Atacama Desert, shows the Milky Way as it peeks above the horizon, with two of the observatory’s telescopes bracketing the starry, dusty band as it stretches across the sky. To the right stands the domed enclosure of the ESO 3.6-metre telescope and its adjacent smaller sibling, the now-decommissioned Coudé Auxiliary Telescope. To the left is the receiver dish for the Swedish–ESO Submillimetre Telescope, also now decommissioned. Stretching into the distance to the left, and nearly at the centre of the image, lie the other buildings and telescope enclosures hosted at La Silla, their outlines silhouetted against the glowing sky. Visible in the far distance are city lights which, although faint in absolute terms, can become noticeable over long exposures such as this one. The soft glow of light just to the left of centre, which gently curves through the sky, ...

28 February 2022: A stunning night view, taken close to the 1.54m Danish Telescope and the 3.6m telescope on the road at La Silla, shows the Milky Way above the horizon, accompanied by the Magellanic Clouds. ESO’s 3.6m Telescope, seen here atop a hill at the centre of the image, is home to HARPS, an instrument dedicated to the discovery of planets outside the Solar System via the radial velocity method. This method enables the detection of a planet by measuring the wobbling motion of the central star caused by the gravitational pull of the planet itself. The towers on the left are the support structures of the BlackGEM telescopes, which had not been installed yet when this image was taken. BlackGEM is an array of telescopes that will search for the light emitted by the optical counterparts of the most powerful gravitational-wave sources, namely colliding neutron stars and black holes. On the ...

15 November 2021: Yes, the bright light you see in the centre of this picture, shining below the Milky Way’s dark, pinkish belt, is in fact the king of the planets in the Solar System! Jupiter is flanked by two hills hosting ESO’s Very Large Telescope (left) and VISTA (right) in the Atacama Desert in Chile. Jupiter is the largest planet in our Solar System and the third brightest object in the night sky, only outshone by the Moon and Venus. Naming it after the god of the sky and thunder is certainly fitting! Mainly made of hydrogen and helium, one of Jupiter’s most distinctive marks is the famous great red spot on its surface, the largest storm in the Solar System. Jupiter has been observed by the 8.2-m telescopes of the VLT on more than one occasion. The VISIR instrument captured a stunning high resolution infrared image of Jupiter, key to understanding ...

13 September 2021: Looking at this photo might make you feel a little topsy-turvy! This Picture of the Week captures both the Northern and Southern Hemisphere at once — the whole night’s sky in one mind-bending image — something that would be impossible to see in real life. To create this image, photographers Petr Horálek and Juan Carlos Casado took two pictures at observatories located at the same latitudes in the Northern and Southern Hemispheres. The top half is a photo taken at the Instituto de Astrofísica de Canarias’ Roque de los Muchachos Observatory in La Palma in the Canary Islands, 29 degrees north of the equator, whilst the bottom half was taken at ESO’s La Silla Observatory in Chile’s Atacama Desert, 29 degrees south of the equator. When digitally stitched together, they create a continuous sweeping view of the night’s sky. One of the most noticeable features in this picture is the ...

30 August 2021: How does a fish see the Milky Way? We can get a pretty good idea thanks to this picture of our galaxy, taken with a fisheye lens from the entrance of the Paranal Residencia at the Paranal Observatory’s Base Camp, located 3 km away from ESO’s Very Large Telescope (VLT). The Paranal Residencia is a true “oasis for astronomers”. Located in the Atacama desert, one of the driest regions on our planet, it is a comfortable and modern building where ESO staff and visitors can rest during their long shifts and withstand the extreme local climatic conditions. The Residencia is a subterranean construction with a 35-metre wide glass-covered dome, which brings in natural light, and a swimming pool, which helps the staff to relax and also contributes to the building’s humidification system. The building’s facade opens towards the Pacific Ocean, just 12 kilometres away. From its southern latitude, Paranal offers ...

2 August 2021: It looks like a tiny planet but this Picture of the Week actually captures ESO’s La Silla Observatory using a photography technique called stereographic projection, whereby a flat image is projected onto a sphere. La Silla, home to several of the instruments in the ESO family, was inaugurated in 1969. As well as being the first ESO observatory, it has also been at the forefront of many scientific and technological firsts. ESO’s pioneering 3.58-metre New Technology Telescope (NTT) was the first in the world to have a computer-controlled, or “active”, main mirror, leading the way for ESO’s Very Large Telescope (VLT), where all four 8-meter mirrors are active.The High Accuracy Radial velocity Planet Searcher (HARPS) instrument attached to the ESO 3.6-metre telescope is a hugely successful exoplanet hunter, discovering among other things the first ‘Earth-like’ planet in a star’s habitable zone. Above “Planet La Silla” arches the pearlescent arm of ...

19 July 2021: Planets, the Galactic centre, stars, glowing gas, silhouetted mountains, and even a comet — this Picture of the Week, taken near the main entrance building of ESO’s Paranal Observatory, is aglow with all the splendours of the clear Chilean skies. On the horizon, a green object shines like a round, fuzzy blob; this is actually an interplanetary visitor called Comet 252P/LINEAR. This comet was pictured as it soared past the Earth in April 2016, skimming some 5.3 million kilometres away from our planet (quite close by cosmic standards!). Although it was too faint to see with the unaided eye, it showed up beautifully in telescopic observations and images such as this one. Further to the right is another colourful object — a small, pink splash, visible just above the horizon adjacent to the comet. This is the Lagoon Nebula, located approximately 5000 light-years from Earth. It can appear grey to ...

12 July 2021: This eye-catching Picture of the Week was captured from ESO’s Paranal Observatory. Home to ESO’s Very Large Telescope, the observatory sits proudly atop the 2635-metre-high Cerro Paranal in Northern Chile’s Atacama Desert. The four Unit Telescopes of the VLT, seen just right of centre in this panorama, are posing in front of the huge expanse of the Milky Way galaxy, which appears almost like a rainbow made of stars, arching over the site. In the image, the four smaller Auxiliary Telescopes are also visible. Astronomers use different configurations of these telescopes that can be moved around on the tracks situated on the telescope platform. Can you spot the four Auxiliary Telescopes in this image?

5 July 2021: Cerro Armazones is the home of ESO’s upcoming flagship facility, the Extremely Large Telescope (ELT). Located in the Chilean Atacama Desert and just 20 km away from ESO’s Paranal Observatory, home to the Very Large Telescope, Cerro Armazones sits just over 3000 metres above sea level. The isolated nature of this peak is illustrated by a magnificently clear band of the Milky Way galaxy that frames the Armazones crater almost perfectly. This isolation, away from the light pollution of cities, makes the Atacama Desert an ideal location for astronomical facilities, including the ELT, which is set to be “the world’s biggest eye on the sky”. This image, taken on 5 July 2019, shows the excavated mountaintop, currently a construction site. The pouring of concrete for the foundation began in December 2019, and the construction of this epic telescope is expected to be finished later this decade.

21 June 2021: Perched between the cascading arch of the Milky Way and the dark mountainside of La Silla Observatory lies the New Technology Telescope (NTT). Since 1989 this ESO telescope has observed and taken images of our night sky in exquisite detail. Some of its more recent achievements include: the observation of the merging of two neutron stars; a more detailed insight into the structure of asteroids; the analysis of hundreds of planetary nebulae; and even research into planets in far off solar systems. Telescopes with larger primary mirrors are able to capture more light. However, a larger mirror’s perfect shape is more difficult to maintain. Astronomers found that with primary mirrors over five metres in diameter, image quality decreased enormously as gravity pulled them out of shape (NTT is 3.5 meters in diameter and was meant as a pioneer project to allow telescopes with larger mirrors to be built). Active optics, ...

14 June 2021: The dark skies above ESO’s Paranal Observatory, home to ESO’s Very Large Telescope (VLT), yield breathtaking views so clear and so full of stars that you could almost touch them. Standing atop a platform at VLT, ESO Photo Ambassador Petr Horálek reaches towards a standout object in the sky. You may assume this bright body, like many others in the sky, to be a star, but it is in fact a planet in our Solar System: the gas giant Jupiter. Closer to Earth, the four Unit Telescopes (UTs) that comprise the VLT can be seen in the background. Each UT features an 8.2-metre mirror and they operate synergistically to produce some of the sharpest views of the Universe. Accompanying the four UTs are four smaller, moveable Auxiliary Telescopes (ATs) which have 1.8-metre mirrors. The Chilean Atacama desert once again proves its value as the ideal location for ESO’s VLT. ...

3 May 2021: This Picture of the Week appears to show a lone antenna gazing at the sky — but in reality this antenna is far from lonely. It is part of the Atacama Large Millimeter/submillimeter Array (ALMA), a telescope that comprises 66 high-precision antennas spread out across the Chajnantor plateau, located high up in the Chilean Andes. In this image we are treated to a spectacularly multi-coloured view of the sky above ALMA: green airglow hovers above the horizon, the Large Magellanic Cloud peeks out from behind the antenna, and the magnificent sprawl of the Milky Way stretches out overhead. These antennas are optimised to collect light at millimetre wavelengths, between infrared and radio waves, giving ALMA a view of the Universe that is very different to our own. Human eyes have evolved to see visible light while ALMA views the cosmos at longer wavelengths, picking up light from some of the ...

19 April 2021: This panoramic selfie was taken on 9 April 2016 by ESO Photo Ambassador Petr Horálek. Petr was in the Chilean Atacama Desert as a member of ESO’s Fulldome Expedition team, a select group of photographers who captured an array of stunning, ultra-high-definition visuals for use primarily in the ESO Supernova Planetarium & Visitor Centre. The landscape looms large around photographer Petr in this image, making him appear small beneath the striking Chilean sky. He can be seen standing just beneath a column of zodiacal light — perfect positioning that makes this image appear even more otherworldly. The wide, round-topped objects visible here are some of the 12-metre antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA is the largest ground-based astronomical observatory in the world, and is located on the Chajnantor Plateau in Chile at an altitude of 5000 metres. A total of 66 antennas make up the array, and ...

12 April 2021: Great care is taken to ensure that the site for a new telescope will provide the best possible observing conditions. This picture of the week was captured in 2019 by ESO photo ambassador Petr Horálek from the top of Cerro Armazones, Chile, where the Extremely Large Telescope (ELT) is being constructed. Situated in the heart of the Atacama desert, at an altitude of 3046 metres, this high and dry location will be vital to showcase and utilise the ELT’s incredible observational power. This extraordinary panorama of the Atacama desert frames a sprawling view of our own Milky Way galaxy, seen with stunning clarity as a result of the minimum light pollution in this remote area. Massive interstellar dust clouds obscure the more distant starlight, leading to the distinctive “mottled” band in the night sky.

5 April 2021: The Atacama Desert in Chile is one of the darkest and most peaceful astronomical sites on Earth — and has, as a result, proven to be the perfect location for ESO’s various observatories and powerful instruments. This view shows ESO’s Paranal Observatory, home to the behemoth Very Large Telescope (VLT). The constituent telescopes of the VLT can be seen standing sentinel beneath a star-studded sky featuring the glittering arch of our Galaxy, and the glowing Magellanic Clouds (left). As this image demonstrates, the sky over Paranal isn’t completely dark; after sunset, the beauty of the Universe is overshadowed by that of Earth’s own atmosphere, which glows in multiple hues and paints the sky like a watercolour. The playful brushstrokes of the faraway emission nebulae that adorn the Milky Way and the constellation of Orion (The Hunter) in the upper centre of the frame, are joined by the soft swaths of ...

8 March 2021: Even after the Sun has set over ESO’s Paranal Observatory in Chile, the site is not truly dark. Although light pollution is practically non-existent at the remote site high up in the Atacama Desert, as daylight disappears the flowing dunes are instead illuminated by the dazzling light streaming from the stars above. The only artificial illumination for miles around comes from Paranal’s facilities, including the telescopes themselves and the Residencia, photographed here. A true oasis in the desert, the Residencia is a refuge from the harsh environment of the Atacama. The astronomers and other employees who work at ESO’s Paranal Observatory, located just a few kilometres down the road and home to ESO’s Very Large Telescope, can escape the arid environment after a long shift and enjoy a walk through the indoor garden or a dip in the swimming pool. The Residencia’s striking visual design is complemented by its world-leading ...

15 February 2021: It may not be as famous as Halley’s Comet, but Comet 252P/LINEAR can still put on a show! In late March 2016, the comet made one of the closest approaches to Earth of all comets in history — just over 5.3 million kilometres distant, compared to Halley’s closest approach of 87 million kilometres. The light of Comet 252P/LINEAR is not elongated in a classic tail, but instead appears as a soft round glow, tinged green due to molecules of diatomic carbon fluorescing in the sunlight. This image from April 2016 captures the distinctly green comet: you can spot it just above the Milky Way, between the galaxy’s starry arch and the Very Large Telescope (VLT) Unit Telescope at the centre of the frame. ESO’s VLT is located at the Paranal Observatory in Chile, an ideal location for comet-spotting. Paranal is one of the most spectacular observatories in the world, situated ...

1 February 2021: This beautiful photograph of the southern sky was taken by ESO Photo Ambassador Petr Horálek from ESO’s Paranal Observatory in Chile. Petr was not alone at Paranal. Standing to the bottom left of the image, next to an Auxiliary Telescope of the Very Large Telescope Interferometer (VLTI), are astrophotographers Yuri Beletsky and Babak Tafreshi, both of whom are also Photo Ambassadors for ESO. The duo are seen beneath a sky filled with stunning phenomena. The bright, dominant band of the Milky Way cuts across the sky, with the Gum Nebula (Gum 12) appearing at the top of the frame in red. The Large Magellanic Cloud, a satellite galaxy of the Milky Way, is an especially bright blotch to the centre right — just below Canopus, the brightest star in both this view and the southern constellation of Carina. A beautiful green and reddish shimmer is also visible at the bottom ...

25 January 2021: The road to ESO’s La Silla Observatory in the Chilean Atacama Desert appears to curve around the mountain and collide with the downward slope of the Milky Way in this Picture of the Week. Small yellow bulbs light up the road at regular intervals; it is prohibited to use headlights on these roads between dusk and dawn, as even dim lights can interfere significantly with telescope observations. The site enjoys some of the darkest night skies on Earth. The darkness, high altitude, and resulting dry air at La Silla make it an exceptional location for astronomy. In the foreground of this image, the Danish 1.54-metre telescope is performing its nightly observations. Its instruments have allowed astronomers to achieve several “firsts”. In 2005, for example, astronomers observed the afterglows of short gamma-ray bursts and showed that the bursts are likely caused by the dramatic collision of two neutron stars, while in ...