Picture of the Week

15 June 2020: ESO’s La Silla Observatory boasts a remarkably high number of cloud-free nights a year. The billions of stars that make up the Milky Way is a very common sight indeed. The dome shown in this image houses one of three 60-centimetre telescopes that make up the ExTrA project, which had its first light in late 2017. This small group of telescopes is primarily designed to detect distant exoplanets transiting in front of bright and nearby red dwarf stars. The project aims to discover as many transiting planets as possible — including Earth-size planets in the habitable-zone — and to determine their structure and composition. These planets will then be observed by the world’s largest telescopes, in order to characterise their atmospheres.

8 June 2020: In 2016, a team of four world-class astrophotographers and videographers journeyed to ESO’s Paranal Observatory in Chile. Their goal? To capture striking views of the Universe in ultra high definition (UHD) and fulldome formats — perfect for use in planetarium shows! Over the course of a few weeks, the photographers gathered UHD stills, fulldome timelapses, 360-degree panoramas, and more, including a whole host of breathtaking shots of their surroundings. One such shot is this ESO Picture of the Week, which shows Paranal — home to ESO’s Very Large Telescope (VLT) — at night. The stargazer visible to the right of the frame, pointing to the beautiful arc of the Milky Way curving overhead, is ESO Photo Ambassador Babak Tafreshi, one of the aforementioned expedition members. The constituent telescopes of the VLT can be seen scattered across the left of the frame (the four boxy Unit Telescopes, and three of the ...

1 June 2020: One of the most exhilarating results in modern astronomy is the knowledge that the Universe is full of worlds beyond our Solar System, known as exoplanets. Increasing evidence suggests that the majority of stars in the Universe have planets whizzing around them; one such system can be seen in this majestic Picture of the Week. The antennas here are among the 66 that make up the Atacama Large Millimeter/submillimeter Array (ALMA), located on the Chajnantor plateau in Chile. Two bright stars sit directly above the centre antenna; the brightest of these two stars is a triple star system known as Alpha Centauri. An exoplanet named Proxima b was recently discovered orbiting within the habitable zone of one these three stars (Proxima Centauri) by ESO telescopes and other facilities. As Alpha Centauri is the closest star system to Earth, Proxima b is the closest exoplanet to Earth ever discovered. Another world ...

25 May 2020: Posing here under the splendours of the southern sky is Babak A. Tafreshi, one of ESO’s Photo Ambassadors. Babak is standing on part of the massive Miñiques volcanic complex, located in the Antofagasta region of Chile’s Atacama Desert. This region is also home to ESO’s Paranal Observatory, where the Very Large Telescope (VLT) gazes up at the sky, observing exotic phenomena such as gamma-ray bursts, extrasolar planets, and supermassive black holes. Each of the VLT’s constituent telescopes can detect objects roughly four billion times fainter than the naked eye can see, giving it a far richer view of the Universe than is available to humans. However, the skies above the Atacama are some of the clearest and darkest in the world — so it’s little wonder that Babak stands in awe beneath it all. The spectacular swirl of blue above Babak’s head is the Large Magellanic Cloud (LMC), a dwarf ...

18 May 2020: This image shows a pair of interacting galaxies known as Arp 271. Individually, these galaxies are named NGC 5426 and NGC 5427; both are spirals, and both are roughly the same size. Some astronomers believe that these galaxies are in the process of merging to form a single entity. This interaction will create increasing numbers of new stars over the next few million years, some of which can be seen within the “bridge” of gas connecting the two galaxies. This kind of collision and interaction might also happen to our own galaxy, the Milky Way, which is likely to collide with the neighbouring Andromeda Galaxy in about five billion years time. These galaxies lie over 120 million light years away from us, and were discovered by the German-British astronomer William Herschel in 1785. Herschel was a prolific scientist, also discovering both infrared radiation and the planet Uranus. Link: Previous release ...

11 May 2020: Some self-portraits are better than others — and this image of ESO Photo Ambassador Petr Horálek is certainly one of the more impressive! Here, the photographer basks in the light of the glowing Milky Way, dwarfed by the scale and wonder of the view overhead. Horálek is standing at one of the highest and driest locations on Earth, amid the vast array of antennas that make up the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA is located on the 5000-metre-high Chajnantor plateau in the Chilean Atacama Desert.The array sees the Universe in wavelengths of light between infrared and radio — key to observing extremely cold and distant objects — and studies the building blocks of stars, planetary systems, galaxies and life itself. ALMA probes right out to the edge of the observable Universe, and allows astronomers to explore and understand how our cosmos came to be. The dark, clear, dry skies ...

4 May 2020: The arrival of daylight at ESO’s La Silla Observatory reveals the splendour of the Universe beyond our little planet in dazzling detail. The Milky Way stretches overhead as a streaming banner of dust backlit by the light of billions of stars. Clouds of interstellar dust grow thickest towards the constellation of Sagittarius (The Archer), which marks the centre of the galaxy — the core around which the spectacular spiral arms rotate. The Galactic Centre also houses a supermassive black hole that produces huge amounts of energy as it consumes its surroundings (Sagittarius A*). ESO’s telescopes helped to characterise this monstrous black hole. An almost three-decade-long study used several of ESO’s flagship telescopes — including one of the Very Large Telescope’s 8.2-metre Unit Telescopes (Yepun) situated at ESO’s Paranal Observatory, and the 3.5-metre New Technology Telescope (NTT) at La Silla — to track the motions of stars orbiting the centre of ...

27 April 2020: This beautiful Picture of the Week shows the magnificent Milky Way stretching over the Very Large Telescope (VLT) at ESO’s Paranal Observatory, demonstrating the astounding level of detail visible in the night sky from this remote site in the Chilean Atacama Desert. At Paranal, the star-studded Milky Way is so bright that on a dark night it can cast shadows of the people and objects beneath it! This image shows countless stars, dark lanes of dust, and glowing clouds of celestial gas. These clouds are sites of star formation; energetic radiation emanating from newborn stars ionizes the hydrogen in the gas clouds, causing them to glow a rosy red. Below the Milky Way is the Large Magellanic Cloud, a dwarf galaxy orbiting the Milky Way. The night sky is observed every night by the world’s most advanced optical observatory the VLT. This telescope is actually made up of four Unit ...

20 April 2020: This picture of the week shows two of the three new ExTrA telescopes hosted at ESO’s La Silla Observatory in Chile. Situated over 2000 meters above sea level, these telescopes scour the skies for Earth-sized worlds around M class stars, which are stars smaller than the Sun. A “shooting star” flashes across the night sky above the telescopes and towards the horizon of the Atacama Desert in Chile. Shooting stars are not actually stars, but small bits of rock or dust that enter the Earth’s orbit and burn up in the atmosphere. Before they enter Earth’s atmosphere, these tiny celestial bodies are called meteoroids. The dramatic streaks of light caused by meteoroids burning up are not just beautiful and exciting, but also informative. Scientists look at the path and brightness of a meteoroid to determine where in the Solar System it came from and what it is composed of. If ...

13 April 2020: From 18 to 20 July 2017 western Germany endured intense storms. Thunder and lightning storms lit numerous fires and drove water levels to some 1.5 metres high, flooding streets and basements across the region. Although destructive, these storms brought their own impressive beauty. In Garching bei München, home to ESO’s Headquarters, ESO photo ambassador Petr Horálek captured this beautiful photograph of the storm over the road connecting Munich to Berlin. Interestingly, the sky surrounding the storm is tinged with purple. Exotic colours in the sky, such as red, green, orange or purple, usually indicate the presence of charged particles in the atmosphere, often caused by weather systems and cloud formations. The colour of the sky is also related to temperature of any lightning bolts, their distance from us, the way their light is distorted before hitting our eyes, and the time of day, since the angle of sunlight ...

6 April 2020: Surrounded by the gleaming metal of one of ESO's Very Large Telescope’s Unit Telescopes, two engineers are carrying out maintenance work on the telescope’s complex and delicate optical systems. Similar to human eyes, the eyes of ESO’s Paranal Observatory must be constantly checked, maintained and tested in order to continuously provide the very best astronomical images. The huge 8.2-metre Unit Telescope mirrors are housed in protective structures, ensuring that the delicate opto-electronic systems are sheltered from the harsh and dusty desert surroundings. But even with this level of protection, it still pays to spring clean the mirror from time to time! This is vital, as even the slightest contamination can distort the astronomical images received.The fine dust particles of the Atacama desert not only lower image quality, but can also have an abrasive effect on the mirror’s surface. This means that not only does the mirror have to be cleaned, ...

30 March 2020: This Picture of the Week captures the Milky Way streaking across the skies above the Chilean Atacama Desert. Dark wisps of interstellar dust form a turbulent mix with the bright glow of hot gas and billions of stars, creating a scene reminiscent of the thick smoke trail of a rocket after launch. In contrast to the tempestuous sight above, a tower at ESO’s Paranal Observatory stands serenely beneath the evening sky. Paranal is home to the Very Large Telescope (VLT), a ground-breaking observatory composed of four Unit Telescopes and four movable Auxiliary Telescopes. The telescopes can be used in different combinations to form an interferometer, combining the light they collect and allowing astronomers to study the Universe in spectacular resolution. The VLT has achieved many scientific firsts over the years, including tracking individual stars orbiting the centre of the Milky Way at unprecedented speeds. This indicated the presence of a ...

23 March 2020: The entire Universe is constantly on the move, from individual atoms all the way up to massive galaxy clusters. This is beautifully showcased in an image such as this, taken from the Chajnantor plateau some 5000 metres up in the Chilean Atacama Desert. This extremely arid and remote environment is home to the Atacama Large Millimeter/submillimeter Array (ALMA), the largest telescope array in existence. The blurred object is a specialised transporter, caught in the act of carefully carrying one of ALMA’s 66 high-precision antennas to a specific position on the plateau. By arranging the antennas in more extended configurations, astronomers can obtain far more highly spatially resolved images (meaning that the image is more detailed), while more compact configurations give better sensitivity for sources which spread over more of the sky. There’s movement going on above, too. Smooth stretches of cloud sweep across the pristine Chilean sky under the ...

16 March 2020: This picture of the week showcases the night sky over the construction site for the Extremely Large Telescope. A beautiful array of stars and the hazy band of the Milky Way are clearly visible above the site. In order to see the Milky Way so distinctly, one must be in an area with low light pollution, such as the Chilean mountain Cerro Armazones, when there is little or no moonlight. The ELT will be “the world’s biggest eye on the sky” when it begins operating. With a 39-metre primary mirror, the ELT will search the sky in the optical and near-infrared wavelength regions for new exoplanets, specifically Earth-like planets in orbit around other stars. The ELT will also be able to perform a kind of “stellar archaeology,” answering fundamental questions about how planets, primordial stars, primordial galaxies and black holes form and evolve. Perhaps the most exciting goal of the ...

9 March 2020: This beautiful image shows the dense heart of the Milky Way stretched out above one of the Auxiliary Telescopes of ESO's Very Large Telescope (VLT). Such dark and star-studded skies are typical of the VLT’s location in the Chilean Atacama Desert, which offers spectacular views such as this night after night for all of the site’s astronomers, visitors, and staff to enjoy. The VLT is made up of four large Unit Telescopes, and four smaller and movable Auxiliary Telescopes (one of which is shown here). These eight telescopes observe the cosmos both individually and as a team from various orientations and positions, allowing astronomers to study all manner of cosmic objects and phenomena in greater detail than ever before. The array has stimulated a new age of discoveries, with several notable scientific firsts — including the first image of a planet orbiting another star (known as an ...

2 March 2020: The soft glow of the Milky Way pours down like a waterfall over the VLT Survey Telescope (VST) at ESO’s Paranal Observatory. 2635 metres above sea level, the VST has an unparallelled view of the magnificently clear skies above Chile’s Atacama Desert. It is the largest telescope in the world dedicated to observational surveys in visible light, and it contributes to a vast range of studies, from discovering remote Solar System bodies to searching for exoplanet transits, to studying the structure and evolution of our galaxy. Above the VST, a few stars are particularly prominent just outside the main band of the galaxy: the bright reddish star is Betelgeuse, a red supergiant 640 light-years away thought to be on the brink of a supernova explosion. Betelgeuse and Bellatrix, the fainter white star to its left, are the shoulders of Orion the Hunter, one of the most famous and easily recognisable ...

24 February 2020: A new study led by Pierre Vernazza (Laboratoire d’Astrophysique de Marseille, France) conducted using ESO facilities has observed the asteroid Pallas for the first time at extremely high angular resolution. The asteroid could be successfully observed in such great detail thanks to the Adaptive-Optics (AO)-fed SPHERE imager on the Very Large Telescope (VLT). German astronomer Heinrich Wilhelm Matthäus Olbers first discovered Pallas on 28 March 1802. Named for the Greek goddess Pallas Athene, the asteroid — along with many other asteroids discovered in the 19th century — was initially classified as a planet. As time passed and technology improved, Pallas was later reclassified as an asteroid. Today it is famous for being the third-largest asteroid in the Solar System, with an average diameter of 512 km. Although Pallas is the largest known asteroid in the Solar System after Ceres and Vesta, it is the only one of these large asteroids ...

17 February 2020: Located deep in the Chilean Atacama Desert, far from the light pollution associated with human activity, is ESO’s Paranal Observatory: a world-leading research site that enjoys some of the darkest skies on Earth. Paradoxically, it is this extreme darkness that allows the sky to light up in technicolour in this image. The striking radiant light visible in the sky here is a phenomenon called airglow, which lends a magical appearance to the already breathtaking night sky. As the name suggests, airglow is a faint glow in the air created as atoms and molecules in the atmosphere combine and emit radiation. It is only visible in regions where the sky is dark enough that artificial lights do not overwhelm it. This phenomenon was the subject of ESOcast 78. This perspective was captured from the site of VISTA, the Visible and Infrared Survey Telescope for Astronomy. The trail of ...

10 February 2020: Stars are surrounded by something known as a corona — a diffuse aura of plasma that appears to surround them in the sky. For the Sun, we can best see this corona during a solar eclipse, when the Moon passes in front of the Sun and covers our star’s face. The solar corona then appears as a bright ring surrounding the eclipsed Sun. An image of the Sun’s corona as seen during a 1999 eclipse can be seen here. However, there is also the optical phenomenon of a corona, caused by the diffraction of light from a bright object — such as the Sun, other stars, the Moon, and bright planets — by water drops or ice crystals in the Earth’s atmosphere. This is occurring in this unusual image, where a rare corona of the planet Jupiter can be seen above the Atacama Desert in Chile. The beautiful red ...

3 February 2020: This remarkable photo shows the ESO La Silla observatory in the foreground with the planets Venus and Jupiter low in the sky and the Milky Way drifting behind them. Yet it took Zdenek Bardon, the photographer, three nights to capture this stunning image; astrophotographers are subject to the whims of the weather and this photo was no exception. He had to wait three days for a crystal clear night with no clouds and low humidity to capture Venus, Jupiter and the Milky Way in all their glory. La Silla is an exceptional location for astronomy because it has relatively low light pollution which allows the stars to appear crystal clear — although lights from human dwellings are visible on the horizon in this image. The site also offers exceptionally low humidity thanks to its elevation of 2400 metres above sea level. High humidity is a problem for both professional astronomers ...