Picture of the Week 2019

25 March 2019: This astonishing image clearly illustrates why astronomical observatories are usually built in remote, and often inhospitable, places. At ESO’s La Silla Observatory in Chile, the sky is so clear and untroubled by man-made sources of light that it appears as if a brightly-coloured celestial firework display is in progress! This photograph, taken by ESO Photo Ambassador Petr Horálek, has been digitally projected to show as much of the sky as possible. This is why the roads leading to ESO’s 3.58-metre New Technology Telescope (left) and 3.6-metre telescope (right) appear distorted, and the bright river of light that is the Milky Way seems to curve across the sky, stretching from horizon to horizon. Cosmic fireworks aside, this scene is filled with awe-inspiring phenomena. The pink “fireworks” themselves are actually large accumulations of glowing gas known as nebulae. To the right of the Milky Way lie the Magellanic Clouds, two nearby dwarf ...

18 March 2019: It’s impossible to miss the star in this ESO Picture of the Week — beaming proudly from the centre of the frame is the massive multiple star system Tau Canis Majoris, the brightest member of the Tau Canis Majoris Cluster (NGC 2362) in the eponymous constellation of Canis Major (The Great Dog). Tau Canis Majoris aside, the cluster is populated by many young and less attention-seeking stars that are only four or five million years old, all just beginning their cosmic lifetimes. The Tau Canis Majoris Cluster is an open cluster — a group of stars born from the same molecular cloud. This means that all of the cluster’s inhabitants share a common chemical composition and are loosely bound together by gravity. Having been born together, they make an ideal stellar laboratory to test theories of stellar evolution, the chain of events that leads from a star’s birth in a ...

11 March 2019: On the night of 20 January 2019 Coquimbo, Chile shook with the force of a magnitude 6.7 earthquake. Although Coquimbo lies 90 kilometres from ESO’s La Silla Observatory, its effects were far from unnoticed. This unique image shows the earthquake as recorded by the Rapid Action Telescope for Transient Objects (TAROT), a telescope designed to monitor gamma-ray bursts. On the night in question, TAROT was imaging geostationary satellites, which look like static points in the sky as seen from a telescope on the ground. As a result, the stars are recorded as trails, as the Earth rotates on its axis during the exposure. In this picture, three 10 second images, taken in rapid succession on the night of the earthquake, have been overlaid. The first image (left) was started 41 seconds after the start of the earthquake, and the last (right) finishes about 100 seconds after the beginning of the ...

4 March 2019: If you had a brand new state-of-the-art telescope facility, what would you look at first? Researchers at the SPECULOOS Southern Observatory — which comprises four small telescopes, each with a 1-metre primary mirror — chose to view the Lagoon Nebula. This magnificent picture is the result, and is one of the SPECULOOS’ first ever observations. The nebula is a cloud of dust and gas in our galaxy where new stars are being born, and is found roughly 5000 light-years from us. This striking image is made even more impressive by the fact that the SPECULOOS isn’t actually designed to study nebulae. The name says it all — SPECULOOS, the Search for habitable Planets EClipsing ULtra-cOOl Stars. In other words, the primary mission of this telescope facility is to find Earth-like planets orbiting faint nearby stars. The candidates it discovers will be passed over to larger telescopes, such as ESO’s forthcoming ...

25 February 2019: This Picture of the Week is a special treat: a first-light image from the newest resident of ESO’s Paranal Observatory, the SPECULOOS Southern Observatory. This planet-hunting machine aims to observe nearby but dim stars to locate exoplanets for other telescopes — such as ESO’s forthcoming Extremely Large Telescope (ELT) — to study in detail. Comprising four one-metre telescopes, each named after one of Jupiter’s Galilean moons, SPECULOOS promises to open up new frontiers in exoplanet research. This image, however, is obviously not of a faint star, but of a galaxy called NGC 6902. Before a telescope starts its primary mission it must successfully undertake an event called “first light”: the first time it is used for a scientific observation. Astronomers typically pick well-known objects for this initial test of a telescope’s capabilities, which is half demonstration and half celebration. In this case, the team settled on NGC 6902 as the ...

18 February 2019: In December 2018, the comet 46P/Wirtanen passed within 11.6 million kilometres of the Earth — about 30 times the distance from the Earth to the Moon. This close pass gave astronomers the chance to observe the comet in detail, and ALMA (the Atacama Large Millimeter/submillimeter Array) took full advantage. ALMA’s speciality is observing the cooler components of the Universe, such as gas and dust, and the array often focuses on specific molecules. This image is no exception, as it highlights one key thing: the hydrogen cyanide gas in the coma around the comet’s nucleus. But why would scientists be looking for an infamous poison? Well, it turns out that hydrogen cyanide is as common as mystery novels have led us to believe — throughout the cosmos, at least! Because it’s a simple organic molecule that forms relatively easily, it’s been observed in comets, stellar atmospheres, and the clouds of dust ...

11 February 2019: This week’s Picture of the Week highlights another of the 20 images to come out of ALMA’s first Large Program, the Disk Substructures at High Angular Resolution Project (DSHARP). DSHARP explored a number of nearby protoplanetary discs to learn more about the earliest stages of planet formation, and a staggering quantity of data from the project has just been released. This object, called AS 205, is notable for being a multiple star system, one of two such systems imaged by DSHARP (the other being HT Lup). While two discs are discernible here, the lower right disc is in fact shared by two stars in a binary system, so we are actually looking at a system of three fledgling stars. Although most high-resolution studies have so far focused on single stars, multiple systems are far from uncommon in the Universe. It is thought that over half of all stars may exist ...

4 February 2019: This week’s Picture of the Week focuses on one of twenty protoplanetary discs explored and imaged by ALMA’s first Large Program, known as the Disk Substructures at High Angular Resolution Project (DSHARP). The disc is called AS 209, and its substructures are particularly pronounced thanks to its thin, high-contrast rings and almost face-on orientation towards us. Though concentric rings — shown here in particularly beautiful clarity — are a common substructure among such discs, their widths, separations, and number can vary greatly. It’s still unclear how these substructures form, and how planets emerge from them. Quantifying and studying these similarities and differences was a motivator for constructing ALMA, and was the main objective of DSHARP. These details may hold clues to the type of planetary system that will eventually emerge. One interpretation is that there may be a rapid and complex interplay between young protoplanets and the disc itself far ...

28 January 2019: This week’s image shows 20 spectacular protoplanetary discs captured by ALMA’s first Large Program, known as the Disk Substructures at High Angular Resolution Project (DSHARP). In a focused observation effort that included hours of data collected over several months, researchers imaged 20 nearby protoplanetary discs to learn more about the earliest stages of planet formation, and the staggering quantity of data from the project has just been released. It has long been thought that planetary systems are likely to have their origins in so-called protoplanetary discs — compressed circles, spirals or ellipses of gas and dust, which form around protostars in the early stages of their development. The process by which planets emerge from these diffuse discs, however, is not well understood. It is particularly challenging to understand the very earliest stages of their evolution — when dust within a disc coalesces into planetesimals and the seeds of planets are ...

21 January 2019: A star-strewn nighttime sky hangs over the Chilean landscape in this captivating photograph. A broken line of yellow lights weave their way across the dark rolling hills below. These marks the route between ESO’s Paranal Observatory, situated atop Cerro Paranal, and the Residencia, the home-from-home for astronomers, technicians and other staff working at the observatory. Designed to provide a cool refuge against the harsh conditions of the Atacama desert, the Residencia is set into a natural hollow and blends perfectly into its arid surroundings. As well as offices and rooms for visiting astronomers, this desert refuge contains a verdant garden and swimming pool set beneath a 35-m wide glass-covered dome. As befits any building near an astronomical observatory, the Residencia is designed to minimise light pollution and to preserve the exceptionally dark skies above Paranal. This image was taken by astrophotographer and ESO Photo Ambassador Petr Horálek. A long-time collaborator ...

14 January 2019: Hundreds of astronomical objects are visible in this ESO Picture of the Week, including star clusters, nebulae, dust clouds, and other galaxies — most notably the Large and Small Magellanic Clouds, visible to the upper right. However, something much closer to home is vying for our attention. To the far right of the image, a silver arc streaks across the sky. This arc is actually composed of two closely-spaced lines, caused by sunlight bouncing off the antennae of two Iridium communication satellites currently orbiting the Earth. It may be empty now, but this dry, barren section of the Chilean Atacama Desert will soon be bustling with activity. The site has been selected to host the southern part of the Cherenkov Telescope Array (CTA), a remarkable array of 99 antennas that will gaze up at this incredible sky in search of high-energy gamma rays. Gamma rays are a type of electromagnetic ...

7 January 2019: Nuzzled in the chest of the constellation Virgo (the Virgin) lies a beautiful cosmic gem — the galaxy Messier 61. This glittering spiral galaxy is aligned face-on towards Earth, thus presenting us with a breathtaking view of its structure. The gas and dust of the intricate spiral arms are studded with billions of stars. This galaxy is a bustling hub of activity with a rapid rate of star formation, and both a massive nuclear star cluster and a supermassive black hole buried at its heart. Messier 61 is one of the largest members of the Virgo Cluster, which is made up of more than a thousand galaxies, and is itself at the centre of the Virgo Supercluster — to which our Milky Way also belongs. This dazzling beauty was first discovered in 1779, and it has been capturing astronomers’ interest ever since. Set against a dark sky littered with galaxies, ...