Photo de la semaine 2023

7 août 2023: It’s now close to 80 metres high — the mammoth steel structure of the ESO’s Extremely Large Telescope (ELT) dome is taking shape in this Picture of the Week, taken on 2 August 2023 under the light of the full Moon. Right now, engineers and construction workers are assembling the structure of the telescope dome in the Chilean Atacama Desert, with progress visible almost every day. When completed, the ELT will be the world’s biggest eye on the sky for visible and infrared observations. Overall, the ELT project is now more than 50 percent complete. The dome structure visible here will house a pioneering five-mirror optical design, which includes a giant main mirror (M1), 39 metres wide and made up of 798 hexagonal segments. The telescope mirrors and other components are being built by companies in Europe, where work is progressing well too. All of the other systems needed to ...

31 juillet 2023: Can you see ESO’s New Technology Telescope (NTT) peaking out of its enclosure on the right of this Picture of the Week? When this telescope was inaugurated in 1989 it packed innovative technology that laid the foundations for all ground-based telescopes that would follow. The mirrors of professional telescopes are so large and heavy that they bend under their own weight; if left uncorrected, this would yield distorted images. The NTT, which is located at ESO’s La Silla Observatory in Chile, has a flexible main mirror that can change shape during observations. Using a so-called ‘reference star’, the NTT adjusts the mirror's shape to correct these deformations, thus ensuring optimal image quality. This technique, called active optics (not to be confused with adaptive optics) was developed by the late Raymond Wilson at ESO. Today, it is applied to all major modern telescopes, including ESO’s Very Large Telescope (VLT) at Cerro ...

24 juillet 2023: Imagine looking through your door’s peephole and seeing this! This Picture of the Week shows a fisheye view of the 1.52-metre telescope at ESO’s La Silla Observatory in Chile, one of our first telescopes that is now enjoying a second life. ESO was founded in 1962, and only a few years later the 1.52-metre telescope was inaugurated. This telescope had several spectrographs like the Boller & Chivens, ECHELEC and FEROS, which studied spectacular comets, stars with powerful winds and exciting exoplanets among other things. This pioneering telescope was decommissioned in 2002, and FEROS was moved to the MPG/ESO 2.2-metre telescope also at La Silla, where it still searches for distant new worlds. But this wasn’t the end for the 1.52-m telescope. After a 20-year-long shutdown, the telescope was recommissioned and upgraded in 2022 as part of the PLATO Spec international project, led by a Czech team. It will now study ...

17 juillet 2023: Can you see the chameleon in this picture? No? Well, it's camouflaged! Yes, we are joking, but this Picture of the Week actually shows the Chamaeleon Cloud, or IC 2631. In the southern hemisphere, this cloud is visible in the sky for most of the year, and in this image, captured by ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA), you can admire it in infrared light. IC 2631 is a reflection nebula made of dust clouds that reflect the light emitted from nearby stars. The nebula is mainly illuminated by one of the youngest, most massive and brightest stars in its neighborhood, HD 97300, visible to the centre-right of the image. The Chamaeleon Cloud is in fact the brightest nebula in the Chamaeleon Complex, a vast region of gas and dust clouds –– much larger than what this image shows –– where numerous newborn and still-forming stars live. ...

10 juillet 2023: This Picture of the Week shows a beautiful flock of sheep, grazing in the Chilean Andes. No, wait, wait, wait. There's no grass to feed on here, and they are at an altitude of around 5000 metres. Ok, no, they are not sheep. Let’s start again. This Picture of the Week shows the beautiful antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), operated by ESO and its international partners in the Chilean Andes. Ok, that’s better! As you can see, ALMA’s 66 white antennas are not the same size: most of them are 12-metre antennas, and only twelve are 7-metre antennas (see the smaller ones over to the left of the ‘flock’?). They work together as an interferometer, acting like a single big telescope. ALMA observes the light emitted from some of the coldest objects in the Universe, such as the most distant galaxies. These antennas can be physically moved ...

3 juillet 2023: Have you ever seen so many telescopes all together? This Picture of the Week was taken at sunset at ESO’s La Silla Observatory, suspended over an ocean of mountains and soft, foggy clouds. Nestled in the Chilean Atacama Desert at an altitude of 2400 metres, La Silla is far from sources of light pollution and has one of the darkest skies on Earth, which explains why it's packed full with telescopes! How many can you spot here? Let’s take a closer look at a few of them. Almost at the centre of the frame, ESO’s 3.6-metre telescope stands out, with the smaller dome of the Coudé Auxiliary Telescope attached to it. The 3.6 m telescope is home to one of the world’s best extrasolar planet hunters, the so-called High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. The antenna to the left side of the picture is the Swedish-ESO Submillimetre Telescope ...

26 juin 2023: Take a look at this aerial photo of the Atacama Pathfinder Experiment, or APEX for short, sat stoically atop the Chajnator plateau in Chile’s Atacama Desert. This remote, dry location, some 5100 metres above sea level, is the perfect location to uncover the secrets of the so-called “cold universe”, the regions in space only a few tens of degrees above absolute zero. APEX is a 12-metre telescope hosted and operated by ESO on behalf of the Max Planck Institute for Radio Astronomy (MPIfR). It observes at millimetre and submillimetre wavelengths — between infrared and radio waves — where vast cold clouds of interstellar dust and gas glow. These clouds act as the birthplace for new stars and would be obscured in the visible light range. Light collected by APEX is then recorded by different instruments. One of these, known as the Large APEX Bolometer Camera (LABOCA), has an array of ...

19 juin 2023: In Chile’s Atacama desert, ESO’s very own colosseum — the Extremely Large Telescope, or ELT –– is being assembled. As this image taken in early June 2023 shows, progress is moving quickly on the construction site, as the steel frame of the telescope’s dome is pieced together. Parts of the steel backbone running around the edge of the building are fitted together at the ELT base camp before being transported to the platform atop Cerro Armazones using specialised transporters. Not an easy feat given that these pre-assembled steel blocks weigh some 70 tonnes! Once they’re on location, the giant steel Lego-like blocks are hoisted up using the gigantic cranes you see here, and mounted on a rail inserted into trolleys. The entire dome, which will weigh 6,100 tonnes, will rotate on these trolleys when the ELT enters operation. If you peer into the distance, to the right of the yellow ...

12 juin 2023: It might look like there’s not a lot going on in this Picture of the Week, but looks can be deceiving. Far off in the distance, huddled together like penguins in an Antarctic storm, sit the 66 high-precision antennas of the Atacama Large Millimeter/submillimeter Array (ALMA). Operated by ESO together with international partners, ALMA is designed to study the light emitted by the coldest objects in the Universe, such as vast cold clouds in interstellar space. Stretching out either side of the antennas is the empty landscape of the Chajnantor plateau. Sitting at 5,000 m above sea level in the Chilean Andes, this remote location is one of the driest places on Earth. It’s this dryness that makes it the perfect place for observing the signals from the cold Universe which would otherwise be heavily absorbed by water vapour in our atmosphere. ALMA is what’s known as an interferometer, meaning ...

5 juin 2023: This Picture of the Week shows a long exposure image of the BlackGEM telescopes, located at ESO’s La Silla Observatory in Chile. The whitish star trails in the sky are an effect due to the Earth’s rotation on its axis around the southern celestial pole, which gives the impression of the stars’ movement over the course of several hours. To the right hand side of the central telescope the Milky Way is visible, seen here as a particularly bright region, densely packed with streaks of starlight. As these streaks move in circles across the night sky, the viewer gets a sense of tumbling around inside a giant washing machine, as they peer out at the scene through the fisheye lens. BlackGEM, which recently started operating, is an array of three 0.65-metre optical telescopes, which can point at different regions of the sky, searching for some of the most dramatic events ...

29 mai 2023: Sometimes dramatic events are needed to create something stunning. This beautiful structure of filaments and clouds in the southern constellation of Vela are all that remains of a massive star that died in a powerful explosion known as supernova. This is a small section of a larger image taken using the wide-field camera OmegaCAM at the VLT Survey Telescope (VST). Hosted at ESO’s Paranal Observatory in the Chilean desert, the VST is one of the best telescopes in the world to take large images of the sky in visible light. Even though bright stars populate this image, it's hard to not be captivated by the pink gaseous clouds filling up the frame. Some tiny, others thicker, the filaments stretch outwards like tentacles. As they intertwine and cling together, an intricate network is formed which mixes with blurred clouds. But how did they come to be like this? Around 11 000 ...

22 mai 2023: Beaucoup de choses peuvent changer en plus de vingt ans - il suffit de regarder ces photos du Very Large Telescope (VLT) de l'ESO ! À gauche, nous voyons le VLT lorsqu'il était encore en construction au sommet du Cerro Paranal au Chili, tandis qu'à droite, nous le voyons dans toute sa splendeur, tel qu'il est aujourd'hui. Avant de construire les télescopes eux-mêmes, la montagne a dû être abaissée de 28 mètres pour créer la plate-forme des télescopes, ce qui a nécessité l'enlèvement de quelque 350 000 mètres cubes de roches. En 1998, le télescope UT1 (Antu), le télescope le plus à gauche et le plus avancé dans sa construction sur la photo de l'époque, a obtenu sa première image du cosmos - il y a 25 ans cette semaine. Aujourd'hui, le VLT se compose de quatre télescopes dotés de miroirs principaux de 8,2 mètres de diamètre et de quatre ...

15 mai 2023: Have you ever seen a sunset so red? Probably not, since the cause of this reddened twilight sky is something quite dramatic: a volcanic eruption. This Picture of the Week was captured at ESO’s Paranal Observatory in Chile; under the Milky Way, on the top of the dark silhouette of Cerro Paranal, ESO’s Very Large Telescope looks upwards to the sky. On 15 January 2022, the submarine volcano Hunga Tonga–Hunga Ha‘apai erupted in the southern Pacific Ocean. This eruption created shock waves that rippled through the atmosphere, reaching places far from the volcano itself. At ESO’s Paranal and La Silla observatories in Chile, more than 10 000 kilometres away, weather stations detected these atmospheric disturbances. The eruption also launched an ash plume 57 kilometres tall, releasing massive quantities of particles into the atmosphere, including water vapour and dust. Sunlight is scattered and reddened by these tiny dust particles, and this ...

8 mai 2023: The telescope peeking out from its dome is the 1.52-metre telescope at La Silla Observatory. Being over 55 years old, the 1.52-metre is one of the oldest telescopes at ESO and it has participated in laying the foundation for many areas of astronomical research. Being a special telescope in many ways, it also has a twin, the 1.52-metre telescope at the Observatoire de Haute Provence in France. Both telescopes were specifically designed to do stellar spectroscopy and astrophotography, and the 1.52-m in La Silla involved no less than five instruments, including the B&C spectrograph. This instrument captured the spectrum of the Hale-Bopp comet as it passed by in 1995, one of the first recorded spectrums of a comet. After over 30 years of service, the 1.52-m at La Silla was decommissioned in 2002. Still sitting in its dome, it peers out over the vast Atacama Desert, and we get to ...

1 mai 2023: In this colorful Picture of the Week we see a portion of the Gum 10 nebula through the eyes of ESO’s Very Large Telescope in Chile. Gum 10 was discovered by the Australian astronomer Colin Stanley Gum, who in 1955 published a catalogue with more than 80 similar diffuse nebulae. The energetic ultraviolet radiation from the hot blue stars in Gum 10 ionise the gas in the nebula, stripping electrons away from their atoms. When these electrons combine again with the atoms, they emit light at very specific colours or wavelengths. The red shade in this image comes from hydrogen, the most abundant element in the Universe. The dark areas are dense clouds of dust that partially block our view of the objects behind them. This image, taken with the FORS2 instrument, was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, ...

24 avril 2023: This Picture of the Week shows a newly-formed planet with a mass similar to Jupiter’s orbiting the star HD 169142. The star has a disc around it, and as the protoplanet moves it carves a circular gap in the disc, as seen in the first image. But how was this planet found? Astronomers observed the system over several years with the SPHERE instrument at ESO’s Very Large Telescope in Chile. A new re-analysis of this data, led by Iain Hammond from Monash University in Australia, confirmed the presence of this protoplanet, which moves around the star at a distance somewhat larger than that between Neptune and the Sun. They also identified a spiral wake that the protoplanet leaves behind as it rearranges part of the material in the disc, much like a boat can create a wake as it moves through water. A protoplanet forms during the early stages of ...

17 avril 2023: This Picture of the Week shows the young stellar object 244-440 in the Orion Nebula observed with ESO’s Very Large Telescope (VLT) –– the sharpest image ever taken of this object. That wiggly magenta structure is a jet of matter launched close to the star, but why does it have that shape? Very young stars are often surrounded by discs of material falling towards the star. Some of this material can be expelled into powerful jets perpendicularly to the disc. The S-shaped jet of 244-440 suggests that what lurks at the center of this object isn’t one but two stars orbiting each other. This orbital motion periodically changes the orientation of the jet, similar to a water sprinkler. Another possibility is that the strong radiation from the other stars in the Orion cloud could be altering the shape of the jet. These observations, presented in a new paper led by ...

10 avril 2023: Don’t worry, no planets were harmed in the making of this Picture of the Week! The powerful laser beams seen here are installed in one of the four 8.2-m telescopes of ESO’s Very Large Telescope (VLT) in Chile. They allow astronomers to obtain very sharp images of the cosmos by correcting the blur caused by turbulence in the atmosphere, but how? The lasers are tuned to a very specific colour that excites sodium atoms floating 90 km above the ground, making them glow. This creates artificial “stars” high up in the sky, whose rapid twinkling is monitored in real time by special sensors. Then, instructions are sent to the telescope’s deformable secondary mirror, which quickly reshapes itself to counteract the atmospheric distortion. And all of this happens at millisecond speeds! This technique, known as adaptive optics, can also use real stars as a reference to measure the turbulence. But there ...

3 avril 2023: From the long eastward shadows of the telescopes in this Picture of the Week we can see that it’s almost the beginning of a long night shift of stargazing for the telescopes at ESO’s La Silla Observatory. In the foreground of this picture is the BlackGEM array, designed to hunt for the visible light of gravitational wave sources. If you then follow the road up to the summit of La Silla you will pass several ESO telescopes including the 1-metre Schmidt telescope and the New Technology Telescope, until you finally reach the 3.6-metre telescope at the top, home to the HARPS planet hunter. La Silla mountain is ideally situated for an observatory as its isolated location means there is very little light pollution. It is also in Chile’s extremely dry Atacama desert at an altitude of 2400 metres, meaning there’s hardly ever a cloud in the sky and almost every ...

29 mars 2023: The circled spot in this Picture of the Week has almost disappeared. What happened? This sequence of images, taken in optical light with ESO’s Very Large Telescope, shows the gamma-ray burst GRB 221009A fading away. Gamma-ray bursts are the most luminous phenomena that we know of in the universe, and GRB 221009A is the brightest one yet as seen from Earth. The burst was detected in October 2022 by several gamma-ray space telescopes, such as NASA's Swift and Fermi and ESA’s INTEGRAL. Then, a few hours after the initial detection, ESO’s X-shooter instrument at the VLT took a spectrum, which provided the first distance measurement to the explosion of approximately 2400 million light years. Thanks to this distance measurement, a team of astronomers led by Daniele Bjørn Malesani (Radboud University, the Netherlands; DAWN/Niels Bohr Institute, Denmark) ruled out an origin in the Milky Way, although the burst is still much ...