Starship Asterisk*

Image Credit: ESO/Petr Horálek

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Cerro Armazones is the home of ESO’s upcoming flagship facility, the Extremely Large Telescope (ELT). Located in the Chilean Atacama Desert and just 20 km away from ESO’s Paranal Observatory, home to the Very Large Telescope (VLT), Cerro Armazones sits just over 3000 metres above sea level. The isolated nature of this peak is illustrated by a magnificently clear band of the Milky Way galaxy that frames the Armazones crater almost perfectly. This isolation, away from the light pollution of cities, makes the Atacama Desert an ideal location for astronomical facilities, including the ELT, which is set to be “the world’s biggest eye on the sky”.

This image, taken on 5 July 2019, shows the excavated mountaintop, currently a construction site. The pouring of concrete for the foundation began in December 2019, and the construction of this epic telescope is expected to be finished later this decade.

Image Credit: ESA/Hubble & NASA, W. Harris

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Two things capture your attention in this spectacular Picture of the Week, which was taken using Hubble’s Wide Field Camera 3 (WFC3): the two enormous galaxies that flank the left and right sides of the image. The galaxy on the left is a lenticular galaxy, which rejoices in the name of 2MASX J03193743+4137580. The side-on spiral galaxy on the right is more simply named UGC 2665. Both galaxies lie approximately 350 million light-years from Earth, and they both form part of the enormous Perseus galaxy cluster.

Perseus is an important figure in Greek mythology, renowned for slaying Medusa the Gorgon — who is herself famous for the unhappy reason that she was cursed to have living snakes for hair. Given Perseus’s impressive credentials, it seems appropriate that the eponymous galaxy cluster is one of the biggest objects in the known Universe, consisting of thousands of galaxies, only a few of which are visible in this image. The wonderful detail in the image is thanks to the WFC3’s powerful resolution and high sensitivity. The WFC3 is sensitive to both visible and infrared light, so those are the wavelengths that are captured in this image. The Perseus supercluster looks very different at other wavelengths. Whilst in this image the spaces between the galaxies appear dark and peaceful, when the X-ray emission is observed the Perseus cluster appears to be burning with bright intense light.

Image Credit: ESO/Petr Horálek

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This eye-catching Picture of the Week was captured from ESO’s Paranal Observatory. Home to ESO’s Very Large Telescope, the observatory sits proudly atop the 2635-metre-high Cerro Paranal in Northern Chile’s Atacama Desert.

The four Unit Telescopes of the VLT, seen just right of centre in this panorama, are posing in front of the huge expanse of the Milky Way galaxy, which appears almost like a rainbow made of stars, arching over the site.

In the image, three out of the four smaller Auxiliary Telescopes are also visible. Astronomers use different configurations of these telescopes that can be moved around on the tracks situated on the telescope platform. Can you spot all three Auxiliary Telescopes in this image?

Image Credit: ESA/Hubble & NASA, E. Noyola

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This image shows the globular cluster NGC 6380, which lies around 35,000 light-years from Earth, in the constellation Scorpio (The Scorpion). The very bright star at the top of the image is HD 159073, which is only around 4000 light-years from Earth, making it a much nearer neighbour to Earth than NGC 6380. This image was taken with Hubble’s Wide Field Camera 3 (WFC3), which, as its name suggests, has a wide field of view, meaning that it can image relatively large areas of the sky in enormous detail.

NGC 6380 is not a particularly exciting name, but it indicates that this cluster is catalogued in the New General Catalogue (NGC), which was originally compiled in 1888. This cluster has, however, been known by many other names. It was originally discovered by James Dunlop in 1826, and he rather immodestly named it Dun 538. Eight years later, in 1834, it was independently rediscovered by John Herschel and he (similarly immodestly) went on to name it H 3688. The cluster was re-rediscovered in 1959 in Paris by Pişmiş, who catalogued it as Tonantzintla 1 — and who, to continue the pattern, also referred to it as Pişmiş 25. In addition to its colourful history of rediscovery, up until the 1950s NGC 6380 was thought to be an open cluster. It was A. D. Thackeray who realised that it was in fact a globular cluster. Nowadays, this cluster is reliably recognised in widely available catalogues as a globular cluster, and referred to simply as NGC 6380.

Image Credit: ESO/Petr Horálek

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Planets, the Galactic centre, stars, glowing gas, silhouetted mountains, and even a comet — this Picture of the Week, taken near the main entrance building of ESO’s Paranal Observatory, is aglow with all the splendours of the clear Chilean skies.

On the horizon, a green object shines like a round, fuzzy blob; this is actually an interplanetary visitor called Comet 252P/LINEAR. This comet was pictured as it soared past the Earth in April 2016, skimming some 5.3 million kilometres away from our planet (quite close by cosmic standards!). Although it was too faint to see with the unaided eye, it showed up beautifully in telescopic observations and images such as this one.

Further to the right is another colourful object — a small, pink splash, visible just above the horizon adjacent to the comet. This is the Lagoon Nebula, located approximately 5000 light-years from Earth. It can appear grey to an observer using a small telescope or binoculars because the human eye has poor colour sensitivity at low light levels, but in long-exposure photos its fantastically vibrant colours shine through. The most prominent constellation in this window on the sky is Scorpius (The Scorpion), but its stars are easily outshone by the “whitish” planetary giant Saturn, and the red-hued Mars. The rest of the sky is lit up in a palette of soft colours by natural airglow.

The eerily backlit mountain peak on the left of the frame is Cerro Armazones, the peak upon which the Extremely Large Telescope (ELT) is currently under construction. When the ELT sees first light, it will be the world’s biggest eye on the sky, and is expected to make significant advances in the study of exoplanets, supermassive black holes, the early Universe, and the nature of dark energy and dark matter.

Image Credit: ESA/Hubble & NASA, A. Newman, M. Akhshik, K. Whitaker

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The centre of this image from the NASA/ESA Hubble Space Telescope is framed by the tell-tale arcs that result from strong gravitational lensing, a striking astronomical phenomenon which can warp, magnify, or even duplicate the appearance of distant galaxies.

Gravitational lensing occurs when light from a distant galaxy is subtly distorted by the gravitational pull of an intervening astronomical object. In this case, the relatively nearby galaxy cluster MACS J0138.0-2155 has lensed a significantly more distant quiescent galaxy — a slumbering giant known as MRG-M0138 which has run out of the gas required to form new stars and is located 10 billion light years away. Astronomers can use gravitational lensing as a natural magnifying glass, allowing them to inspect objects like distant quiescent galaxies which would usually be too difficult for even Hubble to resolve.

This image was made using observations from eight different infrared filters spread across two of Hubble’s most advanced astronomical instruments: the Advanced Camera for Surveys (ACS) and the Wide Field Camera 3 (WFC3). These instruments were installed by astronauts during the final two servicing missions to Hubble, and provide astronomers with superbly detailed observations across a large area of sky and a wide range of wavelengths.