Picture of the Week

11 December 2017: This image captures the moment that a supermoon seemed to rest on top of the Chilean mountains, seen from 4.5 kilometres distance from the summit of La Silla. Although not terribly interesting from a scientific perspective, during this relatively rare event the Moon is a little closer to Earth, making its diameter appear about 10% larger in the sky. A supermoon occurs when a full Moon coincides with its perigee — the point in the Moon’s elliptical orbit at which it is nearest to Earth. A full Moon occurs on average every 30 days, and is at its perigee every 28 days. Three or four times a year these two events occur at almost the same time, creating a supermoon. An astrologer, Richard Nolle, first coined the term supermoon over 30 years ago, but it has only recently come into popular astronomical usage. Before they were known as supermoons, astronomers ...

4 December 2017: These images were taken by ESO’s SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) instrument, installed on ESO’s Very Large Telescope (VLT) at the Paranal Observatory, Chile. These strikingly-detailed views reveal four of the millions of rocky bodies in the main asteroid belt, a ring of asteroids between Mars and Jupiter that separates the rocky inner planets of the Solar System from the gaseous and icy outer planets. Clockwise from top left, the asteroids shown here are 29 Amphitrite, 324 Bamberga, 2 Pallas, and 89 Julia. Named after the greek goddess Pallas Athena, 2 Pallas is about 510 kilometres wide. This makes it the third largest asteroid in the main belt and one of the biggest asteroids in the entire Solar System. It contains about 7% of the mass of the entire asteroid belt — so hefty that it was once classified as a planet. A third of the size of 2 Pallas, ...

27 November 2017: A clear sky, a striking sunset, and the futuristic curves of a state-of-the-art planetarium and visitor centre — what more could you ask for in an ESO Picture of the Week? However, this image has something else up its sleeve to delight us: a sun pillar. This softly-glowing column of light seems to rise from the horizon near the setting Sun, illuminating the sky above it. This illusion is created by millions of tiny ice crystals — usually flat and hexagonal in shape — in our atmosphere, which reflect sunlight to form an apparent beam. Sun pillars are typically seen when the Sun is low in the sky, or when it has dipped below the horizon. The last rays of sunlight have also interacted with particles in the clouds above, which have scattered the light to create a brilliant array of oranges, yellows, reds, and pinks in the sky above ...

20 November 2017: This Picture of the Week shows a huge cloud of gas around the distant quasar SDSS J102009.99+104002.7, taken by the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT) at the Paranal Observatory. Quasars are the luminous centres of active galaxies, which are kept active by material falling onto the central supermassive black hole. This quasar and its surrounding cloud are at a redshift larger than 3, meaning that they are seen as they were only about 2 billion years after the Big Bang. The cloud of gas (or nebula) surrounding the quasar is known to astronomers as an Enormous Lyman-Alpha Nebula (ELAN). These types of nebula are massive structures of gas which formed in the early Universe, and they can help astronomers to learn how angular momentum — which explains the observed rotation of more recent galaxies — was created in the Universe. Thanks to the ...

13 November 2017: Measuring more than 300 000 light-years across, three times the diameter of the Milky Way, this colourful bubble of ionised gas is the biggest to ever have been discovered. The enormous bubble contains 10 individual galaxies and is situated in a particularly dense region of a galaxy group called COSMOS-Gr30, 6.5 billion light-years away from Earth. Targeted due to its high density of galaxies, this group is extremely varied — some galaxies are actively forming stars while others are passive; some are bright while others are dim; some are massive and others are tiny. This record-breaking bubble was discovered and studied in detail thanks to the incredible sensitivity of the MUSE instrument, mounted on ESO’s Very Large Telescope. Operating in visible wavelengths, MUSE combines the capabilities of an imaging device with the measuring capacity of a spectrograph, creating a unique and powerful tool that can shed light on cosmological objects ...

6 November 2017: As the Sun sets, the last rays of the day creep through to illuminate ESO’s Very Large Telescope (VLT) as it prepares for another night of cosmos-gazing! This unusual angle reveals the industrial interior of one of the four 8.2-metre Unit Telescopes that comprise the VLT, situated atop Cerro Paranal, Chile. The Unit Telescope enclosures play a vital role in preserving the VLT’s position as the foremost astronomical ground-based observatory in the world. The vast air-conditioning system — seen in this image as the metallic tubing snaking around the telescope — and state-of-the-art dome work together to maintain the perfect observing environment. This housing shelters the telescope from its harsh surroundings and at night shields the sensitive instruments from windy weather conditions, which could warp the shape of the thin primary mirror and blur the observations. The photo was taken by ESO Photo Ambassador Alexandru Tudorică.

30 October 2017: Brilliant blue stars litter the southern sky and the galactic bulge of our home galaxy, the Milky Way, hangs serenely above the horizon in this spectacular shot of ESO’s Paranal Observatory. This image was taken atop Cerro Paranal in Chile, home to ESO’s Very Large Telescope (VLT). In the foreground, the open dome of one of the four 1.8-metre Auxiliary Telescopes can be seen. The four Auxiliary Telescopes can be utilised together, to form the Very Large Telescope Interferometer (VLTI). The plane of the Milky Way is dotted with bright regions of hot gas. The very bright star towards the upper left corner of the frame is Antares — the brightest star in Scorpius and the fifteenth brightest star in the night sky.

23 October 2017: On Saturday 21 October, ESO Headquarters in Garching, Germany, opened its doors for the yearly Open House Day. In conjunction with other facilities 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. Before the doors had even opened at 11:00, people were waiting outside, eager to experience all the different activities available. In total, a record-breaking 5600 people seized the opportunity to have their questions answered by experienced astronomers and to see what’s going on at an organisation at the forefront of astronomical research. The programme included live experiments (like the comet-making experiment here), guided tours, an exhibition on the ESO observatories, talks from ESO scientists, and a live connection to the ESO observatories in Chile. Visitors could also test some of the interactive demonstrations which will be on display in the exhibition of the ESO Supernova ...

16 October 2017: This image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows V1247 Orionis, a young, hot star surrounded by a dynamic ring of gas and dust, known as a circumstellar disc. This disc can be seen here in two parts: a clearly defined central ring of matter and a more delicate crescent structure located further out. The region between the ring and crescent, visible as a dark strip, is thought to be caused by a young planet carving its way through the disc. As the planet orbits around its parent star, its motion creates areas of high pressure on either side of its path, similar to how a ship creates bow waves as it cuts through water. These areas of high pressure could become protective barriers around sites of planet formation; dust particles are trapped within them for millions of years, allowing them the time and space to clump together and ...

9 October 2017: This family portrait was captured by veteran ESO Photo Ambassador Alexandru Tudorică, and shows all of the telescopes residing at ESO’s La Silla Observatory in Chile. Looming over its relatives, ESO’s 3.6-metre telescope gleams on the far left of the image. Home to the High Accuracy Radial velocity Planet Searcher (HARPS) instrument, the 3.6-metre telescope is the world’s foremost ground-based planet hunter. ESO’s New Technology Telescope (NTT) can be seen on an adjoining peak, easily visible as the next-largest family member. The NTT has been a testbed for pioneering technologies — such as active optics — that are now standard features on telescopes around the world, including ESO’s Very Large Telescope (VLT). The smaller domes of more ESO-operated, collaborative, and decommissioned telescopes can be seen emerging from the mountain terrain, as can the site’s main access road, which winds up the sun-bathed mountainside towards the site’s various technical and support ...

2 October 2017: It may not look like much, but this blob shows a remarkable star named V766 Centauri (V766 Cen for short) and its close companion. It was first studied and classified a few years ago by researchers using ESO's Very Large Telescope Interferometer (VLTI) when it was found to be something known as a yellow hypergiant, a massive and luminous type of star that is extremely rare — and extremely big! Measuring over 1400 times the diameter of the Sun, V766 Cen was not only the largest star of its type ever discovered, but also one of the ten largest stars ever found. However, a recent study has instead suggested that V766 Cen is likely to be in the phase of life just prior to that of a yellow hypergiant: an evolved red supergiant, which is losing mass so fast that it will eventually transition back into a warmer yellow supergiant ...

25 September 2017: This spectacular spiral galaxy, known as NGC 1964, resides approximately 70 million light-years away in the constellation of Lepus (The Hare). NGC 1964 has a bright and dense core. This core sits within a mottled oval disc, which is itself encircled by distinct spiral arms speckled with bright starry regions. The brilliant centre of the galaxy caught the eye of the astronomer William Herschel on the night of 20 November 1784, leading to the galaxy’s discovery and subsequent documentation in the New General Catalogue. In addition to containing stars, NGC 1964 lives in a star-sprinkled section of the sky. In this view from the Wide Field Imager (WFI) — an instrument mounted on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory, Chile — the star HD 36785 can be seen to the galaxy’s immediate right. Above it reside two other prominent stars named HD 36784 and TYC 5928-368-1 — ...

18 September 2017: Rising up to block part of the star-studded sky, the New Technology Telescope (NTT) cuts a striking and dramatic figure in this ESO Picture of the Week. Located at ESO's La Silla Observatory in the Chilean Atacama Desert, the NTT was inaugurated in 1989. It was the first ever telescope to have a computer-controlled main mirror. This 3.58-metre mirror is very flexible and its shape can be continuously changed, allowing astronomers to counteract deformations due to external influences such as temperature and mechanical stress mid-observation in order to see the objects as clearly as possible. Complementing the NTT’s groundbreaking technology is the innovative design of its housing. Its octagonal dome is relatively small and includes a series of flaps that ventilate the structure with reduced turbulence, allowing air to flow smoothly across the mirror. The dome walls can be opened entirely — as opposed to only opening the roof, as ...

11 September 2017: This unusual Picture of the Week showcases the latest data gathered by ESO’s exoplanet hunter, the High Accuracy Radial velocity Planet Searcher (HARPS), during the ongoing Red Dots campaign, a search for terrestrial planets around our nearest three red dwarf stars: Proxima Centauri, Barnard’s Star, and Ross 154. The campaign was launched earlier in 2017 to build on the 2016 discovery of Proxima b around our nearest stellar neighbour, Proxima Centauri. Red Dots is designed as an open notebook science experiment, meaning the public has access to the data and can even contribute observations. Can you see a new exoplanet in these data of Proxima Centauri? By carefully tracing the movement of a star over time, graphs like these can reveal the presence of exoplanets. Just as a star pulls on its orbiting planets using gravity, planets pull on the star, causing the star to wobble and shift the wavelength ...

4 September 2017: This image, taken by ESO Photo Ambassador Petr Horálek, captures the moment that Yepun (UT4), one of the four 8.2-metre Unit Telescopes comprising ESO’s Very Large Telescope (VLT), shoots a laser beam up into the dark night sky over ESO’s Paranal Observatory in Chile. The laser shown in this image acts as an artificial star, known as a Laser Guide Star, and it is used to help astronomers adjust for the blurring and distorting effects of the Earth’s atmosphere. When observing a patch of sky, astronomers set up a laser guide star nearby and measure the tiny fluctuations in its image. The VLT’s adaptive optics system can then use this reference to correct for the changes and distortions in the intervening atmosphere and produce the sharpest images possible in the main observations. Looming over Yepun is the Large Magellanic Cloud (LMC), a barred spiral galaxy that orbits the Milky Way. ...

28 August 2017: From 6 to 20 August this year, AstroCamp 2017 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 16 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 for several years, it has only recently opened ...

21 August 2017: ESO’s new webcams are being enjoyed by people across the world — and it seems the local wildlife can’t resist taking a peek either. One of the cameras at Paranal Observatory in Chile recently played host to a cattle egret (a type of heron), which chose to settle on the enclosure of one of the Auxiliary Telescopes (ATs) comprising ESO’s Very Large Telescope (VLT) Observatory. Thankfully the AT was dormant, waiting for nightfall to begin observing. The webcams from Apical, which began a 24/7 livestream of the workings of Paranal in late 2016, offer razor-sharp images of the observatory and its surroundings in the serene Atacama Desert. The extreme altitude and arid climate mean that distant mountains can be seen hundreds of kilometres away, while the crystal clear skies create stunning 360-degree panoramic webcam views day and night. It seems the heron was happy with the webcams at Paranal — ...

14 August 2017: During the early evening of 7 August, a partial lunar eclipse was visible in the sky above the ESO Headquarters in Garching bei München, Germany. A lunar eclipse occurs when the Earth, Moon and Sun are aligned, and the Earth casts a shadow on the Moon. This time, only a small part of the Moon entered the Earth’s inner shadow, the umbra, but it still made for a stunning view. While observing from the rooftop of the ESO Headquarters building, ESO Photo Ambassador Petr Horálek captured the eclipse along with spectacular rays from the setting Sun behind him, known as anticrepuscular rays — a union of astronomical and atmospherical phenomena. The Picture of the Week shown here is a compilation of over 50 images of the eclipse, starting from the peak of the eclipse just as the Moon rose above the horizon, to the eclipse’s conclusion when the Moon was ...

7 August 2017: This image captures the route from the Residencia — the guesthouse for visitors to ESO's Paranal Observatory— to the breathtaking heart of the Milky Way, which covers the entire night sky. The site shown here is Cerro Paranal, home to ESO's Very Large Telescope (VLT), a telescope comprising four 8.2-metre Unit Telescopes. The VLT can also act as an interferometer in the form of the appropriately-named VLT Interferometer, or VLTI, by gathering additional light from four smaller Auxiliary Telescopes, which can be independently moved around and placed in different configurations. One of these Auxiliary Telescopes is shown in this image, gazing at the sky with its dome wide open. The road from the observatory to the Residencia appears as a shining thread, weaving amongst the rocky outcrops and hills of the desert environment. The yellow glow is caused by dim security lights — the street lighting is kept to a ...

31 July 2017: This image from the Wide-Field Imager on the MPG/ESO 2.2-metre telescope shows the starry skies around a galaxy cluster named PLCKESZ G286.6-31.3. The cluster itself is difficult to spot initially, but shows up as a subtle clustering of yellowish galaxies near the centre of the frame. PLCKESZ G286.6-31.3 houses up to 1000 galaxies, in addition to large quantities of hot gas and dark matter. As such, the cluster has a total mass of 530 trillion (530 000 000 000 000) times the mass of the Sun. When viewed from Earth, PLCKESZ G286.6-31.3 is seen through the outer fringes of the Large Magellanic Cloud (LMC) — one of the Milky Way’s satellite galaxies. The LMC hosts over 700 star clusters, in addition to hundreds of thousands of giant and supergiant stars. The majority of the cosmic objects captured in this image are stars and star clusters located inside the LMC. The ...