This splendid picture shows the European Southern Observatory's Very Large Telescope (VLT) on Cerro Paranal in the Chilean Atacama desert. The mountaintop, 120 km south of the town of Antofagasta, is a remote haven for scientific exploration.
Its distance from populated areas means that light pollution is essentially non-existent, which helps to guarantee clear views for the telescopes. It also ensures that activity is not disturbed by other human activities, such as traffic on nearby roads or dusty air from mines. The desert location means that moisture in the atmosphere is at a very low level, which contributes to the excellent atmospheric conditions. As well as the VLT, Paranal Observatory is also home to the VISTA telescope on an adjacent peak, from which this photograph was taken. The road which links the two peaks can be seen in the centre of the image, winding through the desert landscape.
The two distinct bright patches seen here in the night sky are the Large and Small Magellanic clouds, which are neighbouring galaxies to the Milky Way, about 160 000 and 200 000 light-years away respectively. The path of the Milky Way itself can be seen on the left of the image. Astronomers use the VLT to study our own galaxy, the neighbouring Magellanic Clouds, and naturally also much more distant galaxies billions of light-years from Earth. On the long and winding road to the stars, observatories like the VLT are our first steps.
On a remote mountaintop, 2600 metres above sea level in the Chilean Atacama Desert, lies the world’s most advanced visible-light observatory. The European Southern Observatory’s Very Large Telescope (VLT) is not only a window on the Universe; it is also a celebration of modern science and technology.
This photograph shows two of the four Unit Telescopes that make up the VLT. With its giant 8.2-metre diameter mirrors, sensitive detectors, and state-of-the art adaptive optics system, the VLT uses cutting-edge technology at every opportunity. Even the telescope enclosures — the domes — are highly advanced, being thermally controlled to reduce air turbulence in the telescope structure.
Every night the VLT studies the sky to make discoveries about the Universe. Visible in this photo, sweeping between the two Unit Telescopes, is the plane of the Milky Way. Containing billions of stars, it is our own corner of the cosmos, but the VLT's vision can peer much deeper than this, our home galaxy, and look out to the extremes of space, all in the name of science and discovery.
This image is available as a mounted image in the ESOshop.
As soon as the Sun sets over the Chilean Atacama Desert, ESO’s Very Large Telescope (VLT) begins catching light from the far reaches of the Universe. The VLT has four 8.2-metre Unit Telescopes such as the one shown in the photograph. Many of the photons — particles of light — that are collected have travelled through space for billions of years before reaching the telescope’s primary mirror. The giant mirror acts like a high-tech “light bucket”, gathering as many photons as possible and sending them to sensitive detectors. Careful analysis of the data from these instruments allows astronomers to unravel the mysteries of the cosmos.
The telescopes have a variety of instruments, which allow them to observe in a range of wavelengths from near-ultraviolet to mid-infrared. The VLT also boasts advanced adaptive optics systems, which counteract the blurring effects of the Earth's atmosphere, producing images so sharp that they could almost have been taken in space.
This image is available as a mounted image in the ESOshop.
Imagine being a fly on the wall of ESO's Very Large Telescope (VLT) at the world's most advanced optical observatory. You could have a view a little like this. Fish-eye photography gives this unusual view of the 8.2-metre diameter telescope, poised and ready to begin gathering light from the deep recesses of the Universe as soon as the dome opens and starlight pours in.
The VLT has four of these 8.2-metre Unit Telescopes, called Antu, Kueyen, Melipal and Yepun. These are the Mapuche names for the Sun, Moon, Southern Cross and Venus. This photograph shows Yepun. The names are from the native language of the indigenous people who live mostly in the area south of the Bio-Bio River, some 500 km south of Santiago de Chile.
The VLT is so powerful that it allows us to see objects four thousand million times fainter than those that can be seen with the unaided eye. This has helped make ESO the most productive ground-based observatory in the world.
NGC 520 — also known as Arp 157 — looks like a galaxy in the midst of exploding. In reality, it’s the exact opposite. Two enormous spiral galaxies are crashing into each other, melding and forming a new conglomerate. This happens slowly, over millions of years — the whole process started some 300 million years ago. The object, about 100 000 light-years across, is now in the middle stage of the merging process, as the two nuclei haven’t merged yet, but the two discs have. The merger features a tail of stars and a prominent dust lane. NGC 520 is one of the brightest interacting galaxies in the sky and lies in the direction of Pisces (the Fish), approximately 100 million light-years from Earth.
This image was taken by the ESO Faint Object Spectrograph and Camera attached to the 3.6-metre telescope at La Silla in Chile. It is based on data obtained through B, V, R and H-alpha filters.
The centre of our own galaxy, the Milky Way, is again in the sights of ESO telescopes. This time it’s the turn of ISAAC, the VLT’s near- and mid-infrared spectrometer and camera.
From Chile’s Atacama Desert, site of the ESO observatories, the Milky Way offers magnificent views, particularly in the southern hemisphere winter, when the central region of our galaxy is most visible (see eso0934). However, the Galactic Centre itself, located about 27 000 light-years away in the constellation of Sagittarius, hides behind thick clouds of interstellar dust, which appear as dark obscuring lanes in visible light, but which are transparent at longer wavelengths such as the infrared. In this image, the infrared observations clearly reveal the dense clustering of stars in the galactic core.
ESO telescopes have been tracking stars orbiting the centre of the Milky Way for more than 18 years, getting the highest resolution images of this area and providing a definitive proof of the existence of a supermassive black hole in the heart of our galaxy (read more in eso0226 and eso0846). Infrared flashes emitted by hot gas falling into the supermassive black hole have also been detected with ESO telescopes (see eso0330).
This representative-colour picture is composed of images taken by ISAAC at near-infrared wavelengths through 2.25, 2.09, and 1.71 µm narrowband filters (shown in red, green and blue respectively). It covers a field of view of 2.5 arcminutes.
Among the myriad of stars in this image shines NGC 2257, a collection of cosmic gems bound tightly by gravity. Many billions of years old, but still sparkling brightly, it is an eye-catching astronomical object.
NGC 2257 is a globular cluster, the name given to the roughly spherical concentrations of stars that orbit galactic cores, but are often found far out from the centres in the halo areas of galaxies. Globular clusters contain very old stars, being typically over 10 billion years old, and can therefore be used like a "fossil record" to learn more about the Universe’s past. They are densely packed, with tens to hundreds of thousands of stars gathered within a diameter of just a few tens of light-years. NGC 2257 lies on the outskirts of the Large Magellanic Cloud (LMC), a satellite galaxy of our own Milky Way. It is one of 15 very old globular clusters in the LMC.
The image is made from data taken with the Wide Field Imager instrument on the 2.2-metre MPG/ESO telescope at La Silla, in B, V and I filters, which are shown here in blue, green and red respectively. The field of view is approximately 20 by 20 arcminutes. These observations were made as part of the ESO Imaging Survey project, which was planned to make public imaging surveys to identify targets for follow-up observations with the Very Large Telescope.
This impressive image, taken on 10 May 2010 by ESO astronomer Yuri Beletsky, beautifully depicts the sky above Paranal. One of the 8.2-metre telescopes of ESO's Very Large Telescope, Yepun, Unit Telescope 4, is seen against the wonderful backdrop of the myriad of stars and dust that makes up the Milky Way. A laser beam is coming out of Yepun, aiming perfectly at the Galactic Centre. When used with the adaptive optics system the artificial star created by the beam allows the telescope to obtain images and spectra that are free from the blurring effect of the atmosphere. When this image was taken, astronomers Stefan Gillessen and Hauke Enkel were using the SINFONI instrument, together with the laser guide star facility, to study the centre of our Milky Way, where a supermassive black hole is lurking.
The field of view of the image is very wide, about 180 degrees. One of the 1.8-metre Auxiliary Telescopes used for interferometry can be seen on the right.
Astronomers using data from ESO's Very Large Telescope (VLT), at the Paranal Observatory in Chile, have made an impressive composite of the nebula Messier 17, also known as the Omega Nebula or the Swan Nebula. The painting-like image shows vast clouds of gas and dust illuminated by the intense radiation from young stars.
The image shows a central region about 15 light-years across, although the entire nebula is even larger, about 40 light-years in total. Messier 17 is in the constellation of Sagittarius (the Archer), about 6000 light-years from Earth. It is a popular target for amateur astronomers, who can obtain good quality images using small telescopes.
These deep VLT observations were made at near-infrared wavelengths with the ISAAC instrument. The filters used were J (1.25 µm, shown in blue), H (1.6 µm, shown in green), and K (2.2 µm, shown in red). In the centre of the image is a cluster of massive young stars whose intense radiation makes the surrounding hydrogen gas glow. To the lower right of the cluster is a huge cloud of molecular gas. At visible wavelengths, dust grains in the cloud obscure our view, but by observing in infrared light, the glow of the hydrogen gas behind the cloud can be seen shining faintly through. Hidden in this region, which has a dark reddish appearance, the astronomers found the opaque silhouette of a disc of gas and dust. Although it is small in this image, the disc has a diameter of about 20 000 AU, dwarfing our Solar System (1 AU is the distance between the Earth and the Sun). It is thought that this disc is rotating and feeding material onto a central protostar — an early stage in the formation of a new star.
This image is available as a mounted image in the ESOshop.
- The research for which these observations were originally made was described in ESO press release eso0416.
The stars rotate around the southern celestial pole during a night at ESO’s La Silla Observatory in northern Chile. The fuzzy parts in the trails on the right are due to the Magellanic Clouds, two small galaxies neighbouring the Milky Way. The dome seen in the image hosts ESO’s 3.6-metre telescope and is home to HARPS (High Accuracy Radial velocity Planet Searcher), the world’s foremost exoplanet hunter. The rectangular building seen in the lower right of the image contains the 0.25-metre TAROT telescope, designed to react very quickly when a gamma-ray burst is detected. Other telescopes at La Silla include the 2.2-metre MPG/ESO telescope, and the 3.58-metre New Technology Telescope, the first telescope to use active optics and, as such, the precursor to all modern large telescopes. La Silla was ESO’s first observing site and is still one of the premier observatories in the southern hemisphere.
The Sun sets at ESO’s Very Large Telescope (VLT) in this image. Taken at the observatory on Cerro Paranal in the dry Atacama Desert of Chile, the observatory’s four 8.2-metre telescopes can be seen preparing for the night ahead. Three of the VLT’s four Auxiliary 1.8-metre Telescopes (AT), used for interferometry, are also visible. The telescopes are seen reflected in the protection cover of one of the AT stations. The ATs are mounted on tracks and can be moved between precisely defined observing positions from where the beams of collected light are combined in the interferometric laboratory. The ATs are very unusual telescopes, as they are self-contained in their own ultra-compact protective domes, and travel with their own electronics, ventilation, hydraulics and cooling systems. Each AT has a transporter that lifts the telescope and moves it from one position to the other. At 2600 metres above sea level, the observing climate is excellent, with little disturbance from clouds.
ESO has grown significantly since 1980, when its European staff originally moved from offices at CERN to a dedicated headquarters building in Garching, near Munich, Germany. In the intervening three decades the number of ESO’s member states has increased from six to fourteen, and the organisation has achieved milestones such as the First Light of the New Technology Telescope at La Silla and of the Very Large Telescope at Paranal, becoming in the process the most productive observatory in the world. Today, ESO is constructing the Atacama Large Millimeter/submillimeter Array at Chajnantor in collaboration with international partners, and is in the detailed design phase of a 40-metre-class European Extremely Large Telescope, which will be “the world’s biggest eye on the sky”.
Over the years, the number of ESO staff working in Garching has increased from about 100 to about 450, as the organisation has grown and tackled these exciting new projects. When the capacity of the headquarters building was exceeded, it became necessary to rent additional office space elsewhere on the Garching Forschungszentrum research campus. A recent development during the summer of 2010 is the construction of several new temporary office buildings, seen on the left in this photograph, which are immediately adjacent to the main headquarters (on the right). These buildings make it possible to bring more of the ESO Garching staff onto the main headquarters site from their scattered offices around the campus, so that people can work more easily together. It is planned that a new permanent building, next to the original headquarters, will be constructed for offices and meeting facilities.
Two of the Atacama Large Millimeter/submillimeter Array (ALMA) 12-metre antennas gaze at the sky at the observatory’s Array Operations Site (AOS), high on the Chajnantor plateau at an altitude of 5000 metres in the Chilean Andes.
Eight antennas have been installed at the AOS since November 2009. More antennas will be installed on the Chajnantor plateau during the next months and beyond, allowing astronomers to start producing early scientific results with the ALMA system around late 2011. After this, the interferometer will steadily grow to reach its full scientific potential, with at least 66 antennas.
ALMA is the largest ground-based astronomy project in existence, and will comprise a giant array of 12-metre submillimetre quality antennas, with baselines of up to about 16 kilometres. An additional, compact array of 7-metre and 12-metre antennas will complement the main array. The ALMA project is an international collaboration between Europe, East Asia and North America in cooperation with the Republic of Chile. ESO is the European partner in ALMA.
This unusual and artistic image, made using a technique known as "solargraphy" in which a pinhole camera captures the movement of the Sun in the sky over many months, was taken from the Atacama Pathfinder Experiment (APEX) telescope on the plateau of Chajnantor. The plateau is also where ESO, together with international partners, is building the Atacama Large Millimeter/submillimeter Array (ALMA). The solar trails in the image were recorded over half a year and clearly show the quality of the 5000-metre altitude site, high in the Chilean Andes, for astronomical observations.
The idea for creating the solargraphs at ESO's telescopes came from Bob Fosbury, an astronomer based at ESO Headquarters in Germany, after learning about the technique from Finnish artist Tarja Trygg. Trygg provided the cameras, known as "cans". The cans are constructed from small black plastic canisters used for storing 35 mm film cassettes. A pinhole in a sheet of aluminium foil is placed over a small aperture drilled into the side of the can, and a rectangle of black and white photographic printing paper is curled and placed snugly around the inside of the can.
Two cans were sent to APEX where David Rabanus, the APEX Station Manager, mounted one facing west of north on the gatepost of the telescope enclosure, close to the telescope itself, and the other on the roof of the generator powerhouse facing east of north. Both were pointed at an elevation of about 45 degrees. The cans at APEX were exposed for a full six months from mid-December 2009 until the southern winter solstice in June 2010. The image from the second can is shown here. It includes the tilted profile of Cerro Chajnantor on the right, silhouetted against the trails of the rising Sun. The mostly unbroken solar trails show that there were some clouds at the ALMA site during the six months — but not many! This solargraph is so sharp that holes in the fleeting clouds over Chajnantor on the few partly cloudy days sometimes managed to create individual "snapshots" of the solar disc (seen as dots in the broken sequences).
The colours appearing in this pinhole camera picture are not related to the actual colours of the scene. The colour comes from the appearance of finely divided metallic silver growing on silver halide grains. With solargraphic images, the photographic paper is not developed but simply scanned with a normal colour scanner after exposure and then "inverted" — switched from negative to positive — in the computer. This reveals the latent image, which in a normal photograph consists of around ten silver atoms per billion atoms of silver halide grain and is usually invisible. On continued exposure however, the latent image clumps grow so that the first visible signs of an image are yellowish, which then darkens to sepia and finally to a maroonish-brown hue as the particle size increases. Eventually the maximum exposure produces a slate-grey shade.
APEX is a collaboration between the Max-Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. The telescope is operated by ESO.
- Article about this series of solargraphs in the ESO Messenger
- Bob Fosbury's Solargraphs
- Tarja Trygg’s Solargraphy page
- A solargraph of Cerro Paranal was ESO Picture of the Week on 15 March 2010
- A solargraph of La Silla is available
After the Sun sets at ESO’s Paranal Observatory darkness descends, but the black sky is speckled with a glorious myriad of sparkling stars. This 15-second exposure demonstrates just how dazzling the skies above Paranal are. Located high in the Atacama Desert in Chile far from any sources of light pollution, on a clear moonless night it is possible to see your shadow cast by the light of the Milky Way alone.
Says visual artist and ESO Photo Ambassador José Francisco Salgado, “The skies at Paranal are among the darkest and steadiest I have photographed. I love photographing observatories and at Paranal it's incredible how you can still see just with starlight and zodiacal light!”
In the image the stars of the Milky Way seem to be pouring forth from the open dome of the telescope. The brightest patch close to the telescope is the Carina Nebula (NGC 3372), which contains some of the most massive stars in our galaxy (see for example eso0905 and eso1031). Near the top of the image are the stars of Crux, the Southern Cross. This constellation, and that of Carina, are in the southern sky and are therefore not visible from most northern latitudes.
The telescope in the image is the fourth 1.8-metre Auxiliary Telescope, part of the Very Large Telescope Interferometer (VLTI). The VLTI consists of four 8.2-metre telescopes, and the four smaller Auxiliary Telescopes, which have mirrors 1.8 metres across. Thanks to the size of the telescopes, their cutting-edge technology, and the excellent conditions at the site, it is no wonder that Paranal is considered the most advanced visible-light observatory in the world.
Spiralling around, 61 million light-years away in the constellation Fornax (the Furnace), NGC 1365 is enormous. At 200000 light-years across, it is one of the largest galaxies known to astronomers. This, plus the sharply defined bar of old stars across its structure is why it is also known as the Great Barred Spiral Galaxy. Astronomers think that the Milky Way may look very similar to this galaxy, but at half the size. The bright centre of the galaxy is thought to be due to huge amounts of superhot gas ejected from the ring of material circling a central black hole. Young luminous hot stars, born out of the interstellar clouds, give the arms a prominent appearance and a blue colour. The bar and spiral pattern rotates, with one full turn taking about 350 million years.
This image combines observations performed through three different filters (B, V, R) with the 1.5-metre Danish telescope at the ESO La Silla Observatory in Chile.
In mid-August 2010 ESO Photo Ambassador Yuri Beletsky snapped this amazing photo at ESO’s Paranal Observatory. A group of astronomers were observing the centre of the Milky Way using the laser guide star facility at Yepun, one of the four Unit Telescopes of the Very Large Telescope (VLT).
Yepun’s laser beam crosses the majestic southern sky and creates an artificial star at an altitude of 90 km high in the Earth's mesosphere. The Laser Guide Star (LGS) is part of the VLT’s adaptive optics system and is used as a reference to correct the blurring effect of the atmosphere on images. The colour of the laser is precisely tuned to energise a layer of sodium atoms found in one of the upper layers of the atmosphere — one can recognise the familiar colour of sodium street lamps in the colour of the laser. This layer of sodium atoms is thought to be a leftover from meteorites entering the Earth’s atmosphere. When excited by the light from the laser, the atoms start glowing, forming a small bright spot that can be used as an artificial reference star for the adaptive optics. Using this technique, astronomers can obtain sharper observations. For example, when looking towards the centre of our Milky Way, researchers can better monitor the galactic core, where a central supermassive black hole, surrounded by closely orbiting stars, is swallowing gas and dust.
This image is available as a mounted image in the ESOshop.
NGC 5426 and NGC 5427 are two spiral galaxies of similar sizes engaged in a dramatic dance. It is not certain that this interaction will end in a collision and ultimately a merging of the two galaxies, although the galaxies have already been affected. Together known as Arp 271, this dance will last for tens of millions of years, creating new stars as a result of the mutual gravitational attraction between the galaxies, a pull seen in the bridge of stars already connecting the two. Located 90 million light-years away towards the constellation of Virgo (the Virgin), the Arp 271 pair is about 130 000 light-years across. It was originally discovered in 1785 by William Herschel. Quite possibly, our own Milky Way will undergo a similar collision in about five billion years with the neighbouring Andromeda galaxy, which is now located about 2.6 million light-years away from the Milky Way.
This image was taken with the EFOSC instrument, attached to the 3.58-metre New Technology Telescope at ESO's La Silla Observatory in Chile. The data were acquired through three different filters (B, V, and R) for a total exposure time of 4440 seconds. The field of view is about 4 arcminutes.
During a night at ESO’s Very Large Telescope (VLT), the stars seem to rotate around the southern celestial pole. The skies over Paranal provide splendid observing opportunities for the astronomers below. At the observatory on Cerro Paranal in the dry Atacama Desert of Chile, one of the observatory’s four 8.2-metre telescopes can be seen on the right performing its nightly task of looking at the heavens. Two of the four 1.8-metre Auxiliary Telescopes are also seen in the picture. The dry, high environment at 2600 metres above sea level, and the extraordinarily advanced equipment makes observing time at the VLT highly sought after by astronomers around the world.
Every year in mid-August the Perseid meteor shower has its peak. Meteors, colloquially known as “shooting stars”, are caused by pieces of cosmic debris entering Earth’s atmosphere at high velocity, leaving a trail of glowing gases. Most of the particles that cause meteors are smaller than a grain of sand and usually disintegrate in the atmosphere, only rarely reaching the Earth’s surface as a meteorite.
The Perseid shower takes place as the Earth moves through the stream of debris left behind by Comet Swift-Tuttle. In 2010 the peak was predicted to take place between 12–13 August 2010. Despite the Perseids being best visible in the northern hemisphere, due to the path of Comet Swift-Tuttle's orbit, the shower was also spotted from the exceptionally dark skies over ESO’s Paranal Observatory in Chile. In order not to miss any meteors in the display, ESO Photo Ambassador Stéphane Guisard set up 3 cameras to take continuous time-lapse pictures on the platform of the Very Large Telescope during the nights of 12–13 and 13–14 August 2010. This handpicked photograph, from the night of 13–14 August, was one of Guisard’s 8000 individual exposures and shows one of the brightest meteors captured. The scene is lit by the reddened light of the setting Moon outside the left of the frame.
Although the comet debris particles are travelling parallel to each other, the meteors appear to radiate from a spot on the sky in the constellation of Perseus (here seen very low on the horizon and partly covered by the VLT enclosures). This effect is due to perspective, as the parallel tracks seem to converge at a distance. The apparent origin in Perseus is what gives the Perseid meteor shower its name.
Around the globe, many thousands of people were out observing the Perseids. Some of them took part in citizen science projects such as Meteorwatch and the annual campaign organised by the International Meteor Organization (IMO). According to the IMO measurements, the 2010 Perseid meteor shower was above normal with a peak activity of over 100 meteors per hour under optimal viewing conditions, but not spectacular. In the coming nights the Perseids will still be visible, but with fewer and fewer meteors night by night.
- More about the 2010 Perseids at the International Meteor Organization: http://www.imo.net/live/perseids2010/
- More about ESO's Photo Ambassadors
- Meteorwatch: http://www.meteorwatch.org/