Picture of the Week

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 ...

24 July 2017: Approximately 95 million light-years away, in the southern constellation of Octans (The Octant), lies NGC 7098 — an intriguing spiral galaxy with numerous sets of double features. The first of NGC 7098’s double features is a duo of distinct ring-like structures that loop around the galaxy’s hazy heart. These are NGC 7098’s spiral arms, which have wound themselves around the galaxy’s luminous core. This central region hosts a second double feature: a double bar. NGC 7098 has also developed features known as ansae, visible as small, bright streaks at each end of the central region. Ansae are visible areas of overdensity — they commonly take looping, linear, or circular shapes, and can be found at the extremities of planetary ring systems, in nebulous clouds, and, as is the case with NGC 7098, in parts of galaxies that are packed to the brim with stars. This image is formed from data ...

17 July 2017: The objects that astronomers call brown dwarfs sit somewhere between the definition of a planet and a star. They are balls of gas with more mass than a planet, but not enough mass to sustain stable hydrogen fusion like a star. Because they hardly emit any visible light, they were only first discovered in 1995 and up until today the majority of known brown dwarfs are within 1500 light-years of us. Now, astronomers using the NACO adaptive optics infrared camera on ESO’s Very Large Telescope have observed the star cluster RCW 38 in the constellation Vela (the Sail), about 5500 light-years away. This Picture of the Week shows the central part of RCW 38; the inserts on the sides show a subset of the brown dwarf candidates detected within the cluster. The scientists found half as many brown dwarfs as stars in the cluster. From these results and from studying ...

10 July 2017: In this scene, one of the most recognisable constellations in the night sky — Orion (The Hunter), with his famous belt and sword — rises over the slumbering Swedish-ESO Submillimetre Telescope (SEST) at ESO’s La Silla Observatory in Chile. This mythical collection of stars sits on the celestial equator, making it visible in both hemispheres. Within Orion itself, the distinctive blue and pink hues of the Orion Nebula are visible just above the stellar trio comprising Orion’s Belt. Hundreds of new stars are being forged in the depths of this stellar nursery. Telescopes have observed numerous stars wrapped in cocoons of gas and dust — shrouds that will transform into protoplanetary discs as the turbulent youngsters mature. This image also captures the noticeably reddish colours of Betelgeuse and Aldebaran — giant stars that belong to the constellations of Orion and Taurus (The Bull) respectively. These stars can be seen to ...

3 July 2017: This picture was taken at the northern tip of the Salar de Atacama — the largest salt flat in Chile. The flat is close to the town of San Pedro de Atacama, a town in northern Chile very popular among Chilean tourists and international visitors. The salt flat is home to two similar freshwater lagoons that lie very close together: the Ojos del Salar, which translates to “Eyes of the Salt Pan”. During the day, the site is visited by tourists, who stop by on their excursions from San Pedro de Atacama. Here, one of the two water-filled holes in the middle of the arid landscape is shown at dusk, when the site is again peaceful and quiet. The eye of water perfectly reflects the view of the sky as it changes from day to night. While the clouds on the right horizon are still been dipped in orange by ...

26 June 2017: This orange blob shows the nearby star Betelgeuse, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). This is the first time that ALMA has ever observed the surface of a star and this first attempt has resulted in the highest-resolution image of Betelgeuse available. Betelgeuse is one of the largest stars currently known — with a radius around 1400 times larger than the Sun’s in the millimeter continuum. About 600 light-years away in the constellation of Orion (The Hunter), the red supergiant burns brightly, causing it to have only a short life expectancy. The star is just about eight million years old, but is already on the verge of becoming a supernova. When that happens, the resulting explosion will be visible from Earth, even in broad daylight. The star has been observed in many other wavelengths, particularly in the visible, infrared, and ultraviolet. Using ESO’s Very Large Telescope astronomers ...

19 June 2017: The region between Mars and Jupiter is teeming with rocky worlds called asteroids. This asteroid belt is estimated to contain millions of small rocky bodies, and between 1.1 and 1.9 million larger ones spanning over one kilometre across. Small fragments of these bodies often fall to Earth as meteorites. Interestingly, 34% of all meteorites found on Earth are of one particular type: H-chondrites. These are thought to have originated from a common parent body — and one potential suspect is the asteroid 6 Hebe, shown here. Approximately 186 kilometres in diameter and named for the Greek goddess of youth, 6 Hebe was the sixth asteroid ever to be discovered. These images were taken during a study of the mini-world using the SPHERE instrument on ESO’s Very Large Telescope, which aimed to test the idea that 6 Hebe is the source of H-chondrites. Astronomers modelled the spin and 3D shape of ...

12 June 2017: This Picture of Week shows the Boomerang Nebula, a protoplanetary nebula, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). The background purple structure, as seen in visible light with the NASA/ESA Hubble Space Telescope, shows a classic double-lobe shape with a very narrow central region. ALMA’s ability to see the cold molecular gas reveals the nebula’s more elongated shape, in orange. Since 2003 the nebula, located about 5000 light-years from Earth, has held the record for the coldest known object in the Universe. The nebula is thought to have formed from the envelope of a star in its later stages of life which engulfed a smaller, binary companion. It is possible that this is the cause of the ultra-cold outflows, which are illuminated by the light of the central, dying star. ALMA looked at the nebula’s central dusty disc and the outflows further out, which span a distance of ...

5 June 2017: Astronomers using the ESO observatories might be a common sight in the Chilean Atacama Desert these days, but they were by no means the first people to call the area home. Although the desert is now dry and inhospitable, it once experienced more abundant rainfall and possessed a far more diverse flora. It has hosted various human civilisations, from the El Molle culture of 700–800 CE through to the Las Ánimas (800–1200 CE) and Diaguita (1200 CE to mid-15th century) peoples. Following the 15th-century Peruvian Inca conquests, the local culture became a mix of Inca and Diaguita. This lasted until the onset of the Spanish conquest in the 1530s, which put an end to an indigenously inhabited Atacama. Signs of this past can be found throughout the area surrounding ESO’s La Silla Observatory. Numerous rocks boasting thousand-year-old carvings — petroglyphs — can be found scattered throughout the region, thought to ...

29 May 2017: Like sentries guarding the heart of our home galaxy, the ESO 3.6-metre telescope and the Coudé Auxiliary Telescope stand tall in this stunning ultra high definition photograph from the La Silla Observatory, situated in the southern outskirts of the Chilean Atacama Desert. Since its inauguration in 1976, the ESO 3.6-metre telescope has undergone various upgrades, including the installation of a new secondary mirror that has allowed the telescope to remain as efficient and productive as ever. Since 2008, the telescope has housed the HARPS spectrograph, the most precise exoplanet hunter in the world. HARPS, the High Accuracy Radial velocity Planet Searcher, is the most successful finder of low-mass exoplanets to date. The now-decommissioned 1.4-metre Coudé Auxiliary Telescope (CAT) is housed in the smaller dome to the right of the 3.6-metre telescope. When active, the telescope fed the 3.6-metre’s Coudé Echelle Spectrometer through a light tunnel, which can be seen connecting ...

22 May 2017: Fomalhaut is one of the brightest stars in the sky. At roughly 25 light-years away the star lies especially close to us, and can be seen shining brightly in the constellation of Piscis Austrinus (The Southern Fish). This image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows Fomalhaut (centre) encircled by a ring of dusty debris — this is the first time this scene has been captured at such high resolution and sensitivity at millimetre wavelengths. Fomalhaut’s disc comprises a mix of cosmic dust and gas from comets in the Fomalhaut system (exocomets), released as the exocomets graze past and smash into one another. This turbulent environment resembles an early period in our own Solar System known as the Late Heavy Bombardment, which occurred approximately four billions years ago. This era saw huge numbers of rocky objects hurtle into the inner Solar System and collide with the young terrestrial planets, ...

15 May 2017: This intriguing image may look like a collection of coloured blobs, but it is actually a high-resolution snapshot of a newborn star enshrouded in dust. Just 1300 light-years away in the Orion Nebula, the star, named HH 212, is remarkably young. The average lifespan of such a low-mass star is around 100 billion years, but this star is only 40 000 years old — truly an infant in stellar terms. In the cores of the vast molecular clouds in star formation regions, an ongoing battle rages; gravity versus the pressure of gas and dust. If gravity wins, it forces the gas and dust to collapse into a hot dense core that eventually ignites — forming a protostar. All the leftover gas and dust form a spinning disc around this baby star, and in many star systems they eventually coalesce to make planets. Such very young protostellar discs have been hard ...

8 May 2017: Sitting amongst the alien landscape of the harsh Atacama, the antennas of the Large Millimeter/submillimeter Array (ALMA) look eerily otherworldly in this ESO Picture of the Week as they are bathed in a neon green light. This light is actually an in-built function of ALMA, not evidence of alien activity! The array’s antennas have a flashing green light that blinks periodically whilst the antennas are in operation, and does not disturb the radio-wavelength observations. This light is not usually quite so visible — this picture was captured using a 10-second exposure, during which time a green flash occurred and spread throughout the image, creating a stark contrast between the neon green of the antennas and the deep blue of the night sky. Jagged ice formations known as penitentes can be seen in the foreground. These form at high altitudes where the low pressure and cold temperatures cause an unusual freezing ...

1 May 2017: Many ESO Pictures of the Week feature distant cosmic objects — mysterious jumbles of stars, gas, dust and more sitting millions of light-years away. This panorama, however, showcases a somewhat more tangible, but no less glorious, beauty — that of our home planet, Earth. Captured as the Sun slips below a false horizon of cloud, the sky glows in such a vivid shade of orange that the desert landscape takes on an almost alien appearance. In fact, the Chilean Atacama desert has been used previously by film crews seeking a Mars-like landscape! This other-worldly look is due to the exceptionally arid climate and the site’s complete isolation. The lack of humidity, rain and light pollution together produce both a dusty, rocky landscape and some of the most spectacularly clear skies found anywhere on Earth. This image was taken by ESO’s Simon Lowery in 2016 from Cerro Armazones, the future home ...