IC 5148 is a beautiful planetary nebula located some 3000 light-years away in the constellation of Grus (The Crane). The nebula has a diameter of a couple of light-years, and it is still growing at over 50 kilometres per second — one of the fastest expanding planetary nebulae known. The term “planetary nebula” arose in the 19th century, when the first observations of such objects — through the small telescopes available at the time — looked somewhat like giant planets. However, the true nature of planetary nebulae is quite different.

When a star with a mass similar to or a few times more than that of our Sun approaches the end of its life, its outer layers are thrown off into space. The expanding gas is illuminated by the hot remaining core of the star at the centre, forming the planetary nebula, which often takes on a beautiful, glowing shape. 

When observed with a smaller amateur telescope, this particular planetary nebula shows up as a ring of material, with the star — which will cool to become a white dwarf — shining in the middle of the central hole. This appearance led astronomers to nickname IC 5148 the Spare Tyre Nebula.

The ESO Faint Object Spectrograph and Camera (EFOSC2) on the New Technology Telescope at La Silla gives a somewhat more elegant view of this object. Rather than looking like a spare tyre, the nebula resembles ethereal blossom with layered petals.

ESO’s Paranal Observatory — located in Chile’s Atacama region — is most well known for the Very Large Telescope (VLT), ESO’s flagship telescope facility. However, over the last few years, the site has also become home to two state-of-the-art survey telescopes. These new members of the Paranal family are designed to image large areas of the sky quickly and deeply.

One of them, the 4.1-metre Visible and Infrared Survey Telescope for Astronomy (VISTA), is located on a neighbouring peak not far from the Paranal summit. It is shown in this beautiful photograph taken from Paranal by ESO Photo Ambassador, Babak Tafreshi. VISTA is the world’s largest survey telescope, and has been operating since December 2009.

At the lower right corner of the image, VISTA’s enclosure appears in front of a seemingly endless mountain range, which stretches to the horizon. As sunset approaches, the mountains cast longer shadows, which slowly cover the brownish tones that colour the magnificent landscape that surrounds Paranal. Soon, the Sun will drop below the horizon, and all the telescopes at Paranal will start another night of observations.

VISTA is a wide-field telescope, designed to map the southern sky in infrared light with high sensitivity, allowing astronomers to detect extremely faint objects. The goal of these surveys is to create large catalogues of celestial objects for statistical studies and to identify new targets that can be studied in more detail by the VLT.

Links

• More about the Visible and Infrared Survey Telescope for Astronomy (VISTA)
• ESO Photo Ambassadors

This impressive panoramic image depicts the Chajnantor Plateau — home of the Atacama Large Millimeter/submillimeter Array (ALMA) — with the majestic Licancabur volcano in the background.  Watched over by Licancabur, a icy forest of penitentes (Spanish for “penitents”) cluster in the foreground. The penitentes are a curious natural phenomenon found in high-altitude regions. They are thin spikes of hardened snow or ice, with sharp edges pointing towards the Sun, reaching heights from a few centimetres up to several metres. You can read more about penitentes in a previous Picture of the Week (potw1221).

The Licancabur volcano, with an altitude of 5920 metres, is the most iconic volcano in the area of San Pedro de Atacama, Chile. Its conical shape makes it easily recognisable even from very far away. It is located on the southernmost part of the border between Chile and Bolivia. The volcano contains one of the world’s highest lakes in its summit crater. This lake has attracted the attention of biologists, who are interested on studying how microscopic organisms can survive in it, despite the very harsh environment of intense ultraviolet radiation, the thin atmosphere, and cold temperatures. The survival strategies of microscopic life in Licancabur Lake may even give us insights into the possibility of life on ancient Mars.

This photograph was taken by Babak Tafreshi, one of the ESO Photo Ambassadors, near the ALMA site.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• More about ALMA at ESO
• Joint ALMA Observatory
• ESO Photo Ambassadors

Sunset is typically a sign that another working day is over. City lights are slowly switched on as people return home eager to enjoy the evening and a good night’s sleep. However, this does not apply to astronomers working at an observatory such as ESO’s Paranal Observatory in Chile. Observing starts as soon as the Sun has disappeared below the horizon. Everything needs to be ready before dusk.

This panoramic photograph captures the ESO Very Large Telescope (VLT) against a beautiful twilight on Cerro Paranal. The enclosures of the VLT stand out in the picture as the telescopes in them are readied for a night of studying the Universe. The VLT is the world’s most powerful advanced optical telescope, consisting of four Unit Telescopes with primary mirrors 8.2 metres in diameter and four movable 1.8-metre Auxiliary Telescopes (ATs), which can be seen in the left corner of the image.

The telescopes can also work together as a single giant telescope, the ESO Very Large Telescope Interferometer (VLTI), which allows astronomers to observe the finest possible detail. This configuration is only used for a limited number of nights per year. Most of the time, the 8.2-metre Unit Telescopes are used individually.

Over the past 13 years, the VLT has had a huge impact on observational astronomy. With the advent of the VLT, the European astronomical community has experienced a new age of discoveries, most notably, the tracking of the stars orbiting the Milky Way’s central black hole and the first image of an extrasolar planet, which are two of the top three of ESO’s Top 10 Astronomical Discoveries.

The VLT’s four Unit Telescopes are named after celestial objects in Mapuche, which is an ancient native language of the indigenous people of Chile and Argentina. From left to right, we have Antu (UT1; the Sun), Kueyen (UT2; the Moon), Melipal (UT3; the Southern Cross) and Yepun (UT4; Venus).

This photograph was taken by ESO Photo Ambassador, Babak Tafreshi.

This image is available as a Mounted Image in the ESOshop.

#L

A crystal-clear sky on any night is always a joy to behold. But if you are on the Chajnantor Plateau, at 5000 metres altitude in the Chilean Andes and one of the best places in the world for astronomical observations, it could be an experience that you’ll remember for your whole life.

This panoramic view of Chajnantor shows the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) against a breathtaking starry night sky.

In the foreground, we can see some of ALMA’s antennas, working together. The plateau appears curved, because of the effect of the wide-angle lens used. ALMA is the world’s most powerful telescope for studying the Universe at submillimetre and millimetre wavelengths. Construction work for ALMA will be completed in 2013, and a total of 66 of these high-precision antennas will be operating on the site. At the moment, the telescope is in its initial phase of Early Science Observations. Even though it is not fully constructed, the telescope is already producing outstanding results, outperforming all other submillimetre arrays.

In the sky above the antennas, countless stars shine like distant jewels. Two other familiar celestial objects also stand out. First, the image is crowned by the Moon. Second, outshone by the glow of the Moon, it is possible to distinguish the Milky Way as a hazy stripe across the sky. Dark regions within the band are areas where the light from background stars is blocked by interstellar dust.

This photograph was taken by ESO Photo Ambassador, Babak Tafreshi. Babak is founder and leader of The World At Night, an international project to produce and exhibit a collection of stunning photographs and time-lapse videos of the world’s landmarks with a backdrop of the most beautiful celestial wonders.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• More about ALMA at ESO
• Joint ALMA Observatory
• ESO Photo Ambassadors

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO facilities in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

This month, we are showing a part of ESO that feels almost timeless. After a long intercontinental flight to Santiago, or the night-shifts of an observing run at the telescopes, what could be better than a comfortable staging post at which to recover and rest before the next part of the journey? From the organisation’s earliest years, ESO’s Guesthouse in Santiago has provided just this for visitors to the observatory’s sites in Chile. Our Then and Now photographs this month show the guesthouse lounge, in 1996 and the present day.

The guesthouse is a large villa in a quiet part of the Chilean capital. It is renowned among ESO staff and visiting astronomers as a welcome and inviting rest stop on the long journey between Europe and the remote observatory sites. Almost all European astronomers visiting La Silla, Paranal, or Chajnantor are likely to pass through the guesthouse. Here they can recover from the journey, converse with fellow astronomers, prepare for their observation run and — for newcomers — perhaps get their first glimpse of the southern night sky.

It was decided as early as 1964, with the ESO activity increasing in Santiago, to acquire a pied à terre in the city so that ESO would not have to rely on hotels. The purchase of the guesthouse was completed in March 1965, and it was originally used as an administration office as well as a lodge for visitors. However, in the early 1970s the official ESO offices were moved to the new building in Vitacura, a few kilometres away in the city, allowing the guesthouse to be used exclusively for the comfort and convenience of travel-weary astronomers and other staff.

As can be seen in these two photographs, the guesthouse has not changed much over the years. Wireless internet is now available, and a more modern coffee machine has been provided, but the guesthouse remains a relaxed and peaceful sanctuary. The perfect place to unwind and prepare for gruelling yet exciting nights of observations, and perhaps for the next big discovery.

Links

• The historical image
• The present-day image
• Side-by-side comparison of the historical and present-day images

This colourful new view shows the star-forming region LHA 120-N44 [1] in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. This picture combines the view in visible light from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile with images in infrared light and X-rays from orbiting satellite observatories.

At the centre of this very rich region of gas, dust and young stars lies the star cluster NGC 1929. Its massive stars produce intense radiation, expel matter at high speeds as stellar winds, and race through their short but brilliant lives to explode as supernovae. The winds and supernova shock waves have carved out a huge cavity, called a superbubble, in the surrounding gas.

Observations with NASA's Chandra X-ray Observatory (shown here in blue) reveal hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (shown in red) outline where the dust and cooler gas are found. The visible-light view from the MPG/ESO 2.2-metre telescope (in yellow) completes the picture and shows the hot young stars themselves as well as the glowing clouds of gas and dust that surround them.

Combining these different views of this dramatic region has allowed astronomers to solve a mystery: why are N44, and similar superbubbles, giving off such strong X-rays? The answer seems to be that there are two extra sources of bright X-ray emission: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls. This X-ray emission from the edge of the superbubble shows up clearly in the picture.

Links

• NASA’s Chandra X-ray Observatory
• NASA’s Spitzer Space Telescope

Notes

[1] The designation of this object indicates that it was included in the Catalogue of H-alpha emission stars and nebulae in the Magellanic Clouds, compiled and published in 1956 by American astronomer–astronaut Karl Henize (1926–1993). The letter “N” indicates that it is a nebula. The object is often called simply N44.

Imagine that you have just watched a beautiful sunset from the top of Cerro Paranal. As the Atacama Desert silently fades into the night, ESO’s Very Large Telescope (VLT) opens its powerful eyes on the Universe. With this spectacular 360-degree panorama, you can imagine the view that you would have if you were standing there, near the southern edge of the VLT’s platform.

In the foreground, the fourth of the VLT’s Auxiliary Telescopes (AT4) is opening. To its left, the Sun has already set over the Pacific Ocean — covered by clouds below the altitude of Paranal, as usual. Across the rest of the platform, the other three Auxiliary Telescopes are seen in front of the large buildings of the four 8.2-metre Unit Telescopes. Finally, the Residencia and other basecamp facilities are also visible a little distance away, near the right-hand edge of the picture.

As the night begins, imagine that you are immersed in a deep silence, barely interrupted by the wind or by the smooth movement of these giant machines. It is hard to believe that intense activity is going on in the VLT Control Building, located on the slope of the mountain just below the level of the platform, in the direction of the setting Sun. There, astronomers and telescope operators are starting the first observations of the night. 

Links

• This panorama, and others, can be seen as part of a stunning virtual tour of Paranal and Armazones, at: http://www.eso.org/public/outreach/products/virtualtours/armazones.html
• More ESO virtual tours are available at: http://www.eso.org/public/outreach/products/virtualtours/

A powerful laser beam from ESO’s Very Large Telescope (VLT) paints the night sky over the Chilean Atacama Desert in this stunning image taken by Julien Girard. The Earth’s rotation during the 30-minute exposure — and the movement of the laser as it compensated for this — is why the beam appears to fan out. This is also why the stars are stretched into curved trails, revealing subtle differences in their colours.

The laser is used to create a point of light — an artificial star — by making sodium atoms 90 kilometres up in the Earth’s atmosphere glow. Measurements of this so-called guide star are used to correct for the blurring effect of the atmosphere in astronomical observations — a technique known as adaptive optics. While sufficiently bright natural stars are also used for adaptive optics, a laser guide star can be positioned wherever it is needed, meaning that adaptive optics can be used for targets across more of the sky.

The four large enclosures of the VLT’s 8.2-metre Unit Telescopes are visible in the photograph, with the smaller VLT Survey Telescope (VST) in the background. Julien is an ESO astronomer based in Chile, who works at the VLT. On the night this photo was taken, he was supporting observations on the rightmost Unit Telescope, and took the opportunity to set up his camera on a fixed tripod before returning to the control building to make the observations.

The movements of the telescope enclosures during the long exposure also appear as a blur, while faint trails of light, made by people walking across the platform between the telescopes, can also be seen.

Julien submitted this photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

Links

• This photograph, with annotations, on Julien Girard’s Flickr photostream
• Julien Girard’s Flickr photostream
• The “Your ESO Pictures” Flickr group
• The "Your ESO Pictures" announcement

Standing watch over the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), Orion, the Hunter, shines high in the Chilean night sky. With its distinctive hourglass shape and the three bright stars of Orion’s Belt in the centre, the constellation is easily recognisable. Taken from the southern hemisphere, this image shows Orion’s sword above the Belt. The sword is home to one of the most stunning features of the sky — the Orion Nebula — which appears as the middle “star” in the sword, its fuzzy nebulosity visible to the naked eye under good conditions.

The three ALMA antennas visible in the image represent only a small part of the complete ALMA array, which has a total of 66 antennas. ALMA combines the signals from its antennas, separated over distances of up to 16 kilometres, to form a single giant telescope, using a technique called interferometry. While construction is not due to be completed until 2013, early scientific observations began with a partial set of antennas late in 2011.

At 5000 metres altitude on the Chajnantor Plateau in the foothills of the Chilean Andes, in one of the most arid regions in the world, ALMA is guaranteed outstanding observing conditions. A high, dry site such as Chajnantor is needed because water vapour and oxygen in the Earth’s atmosphere strongly absorb the millimetre and submillimetre wavelengths of light at which ALMA is designed to observe.

In this photograph, the antennas were being tested at ALMA’s Operations Support Facility, located at the slightly lower altitude of 2900 metres. Once tested and fully equipped, they were transported up to the Chajnantor plateau to begin their work.

This image was taken by Adrian Russell, who submitted the photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• Adrian Russell’s Flickr photostream
• This photograph on Flickr
• The Your ESO Pictures Flickr group
• The Your ESO Pictures announcement
• More about ALMA at ESO
• The Joint ALMA Observatory

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

This pair of pictures shows a view from the entrance of the Paranal Observatory site in northern Chile, looking towards the summit of Cerro Paranal, as seen in 1987 and in the present day.

The Cerro Paranal region was first scouted out as a possible site for the future Very Large Telescope (VLT) in 1983 by a team including ESO’s Director General at that time, Lodewijk Woltjer (see The Messenger, No. 64, pp 5–8 for more information). In 1987 a dirt road to the summit was constructed and a permanent station for monitoring the conditions was established. The historical picture shows the view at that time.

The site testing results were extremely good — the conditions were clearly better than either ESO’s La Silla Observatory or the other sites then under consideration. They led to the decision to site the VLT on Paranal, which was made by the ESO Council in December 1990 (see eso9015).

Much has changed at Paranal in the 25 years since the historical photograph was taken. The summit of the mountain was leveled and a high-quality road put in place, and of course the observatory’s telescopes themselves were constructed. The complete and fully operational observatory can be seen in the present day photograph. On the summit now stand the four 8.2-metre VLT Unit Telescopes, along with the four smaller 1.8-metre Auxiliary Telescopes, used for interferometry, as well as the 2.6-metre VLT Survey Telescope. At the gate many buildings forming the observatory’s basecamp have been erected. For a view from the opposite direction, looking down from the mountaintop over the basecamp, see the earlier Picture of the Week potw1230.

Links

• The historical image
• The present-day image
• Side-by-side comparison of the historical and present-day images

On Earth, cocoons are associated with new life. There are “cocoons” in space too, but, rather than protecting pupae as they transform into moths, they are the birthplaces of new stars.

The red cloud seen in this image, taken with the EFOSC2 instrument on ESO’s New Technology Telescope, is a perfect example of one of these star-forming regions. This is a view of a cloud called RCW 88, which is located about ten thousand light-years away and is about nine light-years across. It is not made of silk, like a moth’s cocoon, but of glowing hydrogen gas that surrounds the recently formed stars. The new stars form from clouds of this hydrogen gas as they collapse under their own gravity. Some of the more developed stars, already shining brightly, can even be seen peering through the cloud.

These hot young stars are very energetic and emit large amounts of ultraviolet radiation, which strips the electrons from the hydrogen atoms in the cloud, leaving the positively charged nuclei — protons. As the electrons are recaptured by the protons, they can emit H-alpha light, which has a characteristic red glow.

Observing the sky through an H-alpha filter is the easiest way for astronomers to find these star-forming regions. A dedicated H-alpha filter was one of the four filters used to produce this image.

Looking down from a vantage point at the ESO Very Large Telescope on Cerro Paranal in the Chilean Atacama Desert, the observatory’s basecamp stretches out below. The Paranal Residencia, a haven for those working on the mountain, can be seen near the centre with the dome on its roof. To the left of the Residencia, on the other side of the road, is the basecamp’s gymnasium, and to the left of that is the Mirror Maintenance Building (MMB), where the giant VLT mirrors are periodically cleaned and recoated. Behind the MMB is the site’s power station, and further to the left is the mechanical workshop building. Winding up the mountainside in the foreground is the Star Track, a walking path from the Residencia to the summit.

The Sun had set about a quarter of an hour before this photograph was taken, leaving the basecamp bathed in beautiful orange light. This twilight creates gentle shadows which give the hills great depth. Such a sight at Paranal can only be seen during the so-called "golden hours" before sunrise or after sunset, as direct sunlight during the day results in unforgiving lighting contrasts.

This panoramic photograph was created by ESO Photo Ambassador Gerhard Hüdepohl.

Links

• ESO Photo Ambassadors

This photograph shows one of the 12-metre-diameter European antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) being moved at the project’s Operations Support Facility. Since this photograph was taken, this antenna, and others like it, have been put into operation as ALMA has begun scientific observations with a partial array (see eso1137). Most recently, the Call for Proposals for ALMA’s next phase of observations closed on Thursday 12 July. Over 1100 proposals were received from astronomers around the world.

ALMA makes its observations on the Chajnantor plateau at an altitude of 5000 metres. Once construction is completed, ALMA will have an array of 66 high-precision 12-metre- and 7-metre-diameter antennas, spread over distances of up to 16 kilometres, working together as a single telescope at wavelengths of 0.32 to 3.6 millimetres. More than half of the 66 antennas are already on Chajnantor (see ann12035). Twenty-five ALMA antennas are being provided by ESO through a contract with the European AEM Consortium, 25 antennas are being provided by North America, and 16 by East Asia.

The antennas, each weighing about 100 tonnes, are assembled and tested at the Operations Support Facility, high in Chile’s Atacama region, at an altitude of 2900 metres. They are moved from there to the Chajnantor plateau, 5000 metres above sea level, with the help of two specially designed ALMA antenna transporters — huge vehicles that drive on 28 tyres, are 10 metres wide, 20 metres long and 6 metres high, weigh 130 tonnes, and have as much power as two Formula 1 engines. One of the transporters, named Otto, is being used in this photograph, which was taken when the first European antenna was handed over to the observatory in April 2011.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The Cat’s Paw Nebula is revisited in a combination of exposures from the MPG/ESO 2.2-metre telescope and expert amateur astronomers Robert Gendler and Ryan M. Hannahoe. The distinctive shape of the nebula is revealed in reddish puffy clouds of glowing gas against a dark sky dotted with stars.

The image was made by combining existing observations from the 2.2-metre MPG/ESO telescope of the La Silla Observatory in Chile (see ESO Photo Release eso1003) with 60 hours of exposures on a 0.4-metre telescope taken by Gendler and Hannahoe.

The resolution of the existing 2.2-metre MPG/ESO telescope observations was combined (by using their “luminance” or brightness) with the colour information from Gendler and Hannahoe’s observations to produce a beautiful combination of data from amateur and professional telescopes. For example, the additional colour information brings out the faint blue nebulosity in the central region, which is not seen in the original ESO image, while the ESO data contribute their finer detail. The result is an image that is much more than the sum of its parts.

The well-named Cat’s Paw Nebula (also known as NGC 6334) lies in the constellation of Scorpius (The Scorpion). Although it appears close to the centre of the Milky Way on the sky, it is relatively near to Earth, at a distance of about 5500 light-years. It is about 50 light-years across and is one of the most active star formation regions in our galaxy, containing massive, young brilliant blue stars, which have formed in the last few million years. It is host to possibly tens of thousands of stars in total, some of them visible and others still hidden in the clouds of gas and dust.

Links

• Robert Gendler’s website

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Since February 2002 (see eso0205), the Paranal Residencia has provided accommodation for people working shifts at ESO’s flagship observatory site. Paranal, in Chile’s Atacama Desert, is the home of ESO’s Very Large Telescope (VLT). This month, our Then and Now photographs — both taken by ESO Photo Ambassador Gerhard Hüdepohl — give us a unique view of how this oasis in the desert was built.

The historical photograph shows the Residencia under construction at the end of 2000. The building was designed by German architecture firm Auer+Weber, and is based around a subterranean L-shape. The building materials have the same colour as the desert, to help it blend into the landscape, and the partially completed central area of the Residencia is reminiscent of an amphitheatre, with stone tiers open to the cloudless sky.

Today, the Residencia looks quite different! Despite the subterranean location, the building’s distinctive design creates an interior with a feeling of open space. The central hall is protected by a 35-metre-wide glazed dome, which allows natural daylight into the building. The sterile amphitheatre of 2000 is reinvented as a lush tropical garden, with a pool at the bottom. Both the garden and the pool are designed to increase the humidity indoors, allowing staff some respite from the extremely arid conditions outside, in one of the driest places on Earth.

Thanks to the Residencia’s unique design, its fame has also spread beyond the astronomy community.  For example, in 2008 the James Bond movie Quantum of Solace filmed key scenes here, with the Residencia playing the role of the “Perla de las Dunas” hotel [1]. In 2009, the Residencia was selected as one of the “top 10 buildings of the decade” by the UK’s Guardian newspaper (see ann0940), and in 2012, the Paranal Observatory, including the Residencia, was featured in Land Rover’s “Perfect Places” ad campaign (see ann12008).

Notes

[1] For more information about James Bond at Cerro Paranal see eso0807, eso0838, and http://www.eso.org/public/outreach/bond/BondatParanal.html

Links

• The historical image
• The present-day image
• Side-by-side composite of the historical and present-day images
• ESO Photo Ambassadors

On a cold dark night on Mars, in the middle of an arid desert, a narrow road lit by artificial lights winds its way up to a lonely human outpost on the top of an old mountain. Or at least, that’s what a science fiction fan might make of this almost unearthly view.

The photograph actually shows ESO’s Paranal Observatory, home to the Very Large Telescope (VLT), on Earth. Nevertheless, it’s easy to imagine it as a future view of Mars, perhaps at the end of the century. Which is why Julien Girard, who took this photograph, calls it “Mars 2099”.

Located at 2600 metres altitude, ESO’s Paranal Observatory sits in one of the driest and most desolate areas on Earth, in Chile’s Atacama Desert. The landscape is so Martian, in fact, that the European Space Agency (ESA) and NASA test their Mars rovers in this region. For example, an ESA team recently tested the self-steering Seeker rover, as described in ann12048.

This image was taken at twilight, looking southwest towards the VLT, from the VISTA survey telescope on an adjacent peak. To the west lies the Pacific Ocean, only about 12 kilometres from Paranal. Rising up from the Paranal summit, the Milky Way can be seen, bearing the unmistakable mark of the southern sky — the asterism of the Southern Cross.

At Paranal, the skies can be so clear and dark on moonless nights, that the light from the Milky Way alone is enough to cast shadows. This is why ESO chose the site for the VLT, and why the observatory benefits from some of the best observing conditions in the world.

Julien Girard is an ESO astronomer based in Chile, who works at the VLT. He submitted this photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

Links

• ESO announcement, “Self-steering Mars Rover tested at ESO’s Paranal Observatory”
• STFC press release, “Revolutionary navigation system for future Mars rovers”
• This photograph, with annotations, on Julien Girard’s Flickr photostream
• Julien Girard’s Flickr photostream
• The “Your ESO Pictures” Flickr group
• The "Your ESO Pictures" announcement

One of the major enemies of astronomers is the Earth’s atmosphere, which makes celestial objects appear blurry when observed by ground-based telescopes. To counteract this, astronomers use a technique called adaptive optics, in which computer-controlled deformable mirrors are adjusted hundreds of times per second to correct for the distortion of the atmosphere.

This spectacular image shows Yepun [1], the fourth 8.2-metre Unit Telescope of ESO’s Very Large Telescope (VLT) facility, launching a powerful yellow laser beam into the sky. The beam creates a glowing spot — an artificial star — in the Earth’s atmosphere by exciting a layer of sodium atoms at an altitude of 90 km. This Laser Guide Star (LGS) is part of the VLT’s adaptive optics system. The light coming back from the artificial star is used as a reference to control the deformable mirrors and remove the effects of atmospheric distortions, producing astronomical images almost as sharp as if the telescope were in space.

Yepun’s laser is not the only thing glowing brightly in the sky. The Large and Small Magellanic Clouds can be seen, to the left and to the right of the laser beam, respectively. These nearby irregular dwarf galaxies are conspicuous objects in the southern hemisphere, and can be easily observed with the unaided eye. The prominent bright star to the left of the Large Magellanic Cloud is Canopus, the brightest star in the constellation Carina (The Keel), while the one towards the top-right of the image is Achernar, the brightest in the constellation Eridanus (The River).

This image was taken by Babak Tafreshi, an ESO Photo Ambassador.

Notes

[1] The VLT’s four Unit Telescopes are named after celestial objects in the indigenous Mapuche language, Mapudungun. The Unit Telescopes (UTs) are named: Antu (UT1, the Sun); Kueyen (UT2, the Moon); Melipal (UT3, the Southern Cross); and Yepun (UT4, Venus).

Links

• ESO Photo Ambassadors

#L

Many astronomical photographs capture stunning vistas of the skies, and this is no exception. However, there’s something unusual about this panorama. Behind ESO’s Very Large Telescope (VLT), two streams of stars seem to cascade down like waterfalls, or perhaps rise like smoke columns to the heavens. That’s because this panorama captures the entire dome of the sky, from the zenith down to the horizon, a full 360 degrees around. The two streams are in fact a single band: the plane of our galaxy, the Milky Way, as it arcs across the sky from horizon to horizon. As it passes overhead, it appears to spread out across the whole top edge of the panorama, due to the distortion needed to squeeze the full dome of the sky into a flat, rectangular image.

To understand the picture, imagine that the far left side is attached to the far right, creating a loop around you, and that the top edge is drawn together to a single point overhead. Thus, it encompasses the full dome of the sky above you.

On the left side of the image, the silhouette of the observatory’s windsock on its pole can be seen above the building. To the left of the windsock is the bright smudge of the Small Magellanic Cloud, a neighbouring galaxy of the Milky Way. To the right, in the plane of the Milky Way, is the reddish glow of the Carina Nebula. Above that is the darkness of the Coalsack Nebula, next to the Southern Cross, and slightly higher still are the two bright stars of Alpha and Beta Centauri. The four tall buildings in the image house the 8.2-metre-diameter Unit Telescopes (UTs) of the VLT. Between the two UTs on the right is the smaller building of the VLT Survey Telescope. On the right of the image, the planet Venus glows just above the horizon.

This panorama, which shows not only the VLT on the mountaintop of Cerro Paranal, but also the beautiful sky that the observatory studies, was created by ESO Photo Ambassador Serge Brunier. Just as the VLT’s state-of-the-art technology expands our view of the Universe, Serge has used the most advanced photographic techniques to capture an entire hemisphere of the sky in one image — far more than our eyes could see in a single view.

Links

• ESO Photo Ambassadors
• Experience more breathtaking panoramas in ESO’s Virtual Tours

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Our pair of photographs this month show how the computing power used by ESO has changed dramatically over time. Both photographs show Austrian astronomer Rudi Albrecht in front of ESO’s computer systems, but on dates separated by decades.

In the historical image, taken in 1974 in the ESO offices in Santiago, Chile, we can see Albrecht, pencil in hand, poring over code in front of a teletype. He was working on software for the Spectrum Scanner attached to the ESO 1-metre telescope [1] located at the La Silla Observatory. The data were processed in Santiago using the Hewlett Packard 2116 minicomputer which can be seen behind the printer. This bulky computer, with one processor and a breathtaking 16 kilobytes of magnetic-core memory (!), stored the results on magnetic tape, ready for further processing by visiting astronomers on computers at their home institutes. To handle files on tape that were larger than the available memory, Albrecht developed a virtual memory system, which he contributed to the Hewlett Packard Software Center.

The present-day photograph shows Albrecht in the Data Centre at ESO Headquarters in Garching bei München, Germany, which archives and distributes data from ESO’s telescopes. He is in front of a rack containing a system with 40 processor cores, 138 terabytes of storage capacity and 83 gigabytes of RAM — over 5 million times more than the machine used by him back in 1974! Even the tablet computer he is holding far outperforms the older machine, and provides a modern alternative to pencil and paper.

Over the years, ESO’s computing systems have developed to handle the flood of scientific data from the observatory’s telescopes. Advances in telescope, detector, and computer technology mean that observatories now produce massive quantities of images, spectra, and catalogues. For instance, the two survey telescopes at Paranal, the VST and VISTA, together produce over 100 terabytes of data per year. It’s a far cry from the days of magnetic tape and 16 kilobytes of memory!

Notes

[1] The ESO 1-metre telescope was decommissioned in 1994.

ESO Photo Ambassador Babak Tafreshi snapped this remarkable image of the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), set against the splendour of the Milky Way. The richness of the sky in this picture attests to the unsurpassed conditions for astronomy on the 5000-metre-high Chajnantor plateau in Chile’s Atacama region.

This view shows the constellations of Carina (The Keel) and Vela (The Sails). The dark, wispy dust clouds of the Milky Way streak from middle top left to middle bottom right. The bright orange star in the upper left is Suhail in Vela, while the similarly orange star in the upper middle is Avior, in Carina. Of the three bright blue stars that form an “L” near these stars, the left two belong to Vela, and the right one to Carina. And exactly in the centre of the image below these stars gleams the pink glow of the Carina Nebula (eso1208).

ESO, the European partner in ALMA, is providing 25 of the 66 antennas that will make up the completed telescope. The two antennas closest to the camera, on which the careful viewer can find the markings “DA-43” and “DA-41”, are examples of these European antennas. Construction of the full ALMA array will be completed in 2013, but the telescope is already making scientific observations with a partial array of antennas.

Babak Tafreshi is founder of The World At Night, a programme to create and exhibit a collection of stunning photographs and time-lapse videos of the world’s most beautiful and historic sites against a night-time backdrop of stars, planets and celestial events.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

#L

Babak Tafreshi, one of the ESO Photo Ambassadors, has captured a curious phenomenon on the Chajnantor plateau, the site of the Atacama Large Millimeter/submillimeter array (ALMA).

These bizarre ice and snow formations are known as penitentes (Spanish for “penitents”). They are illuminated by the light of the Moon, which is visible on the right on the photograph. On the left, higher in the sky, the Large and Small Magellanic Clouds can be faintly seen, while the reddish glow of the Carina Nebula appears close to the horizon on the far left.

The penitentes are natural marvels found in high-altitude regions, such as here in the Chilean Andes, typically more than about 4000 metres above sea level. They are thin spikes and blades of hardened snow or ice, which often form in clusters, with their blades pointing towards the Sun. They attain heights ranging from a few centimetres, resembling low grass, up to five metres, giving an impression of an ice forest in the middle of the desert.

The precise details of the mechanism that forms the penitentes are still not completely understood. For many years, people of the Andes believed the penitentes to be the result of strong winds prevalent in the Andes mountains. However, the strong winds have only a limited role in shaping these icy pinnacles. Nowadays, it is believed that they are the product of a combination of physical phenomena.

The process begins with sunlight shining on the surface of the snow. Due to the very dry conditions in these desert regions, the ice sublimes rather than melts — it goes from solid to gas without melting and passing through a liquid water phase. Surface depressions in the snow trap reflected light, leading to more sublimation and deeper troughs. Within these troughs, increased temperature and humidity means that melting can occur. This positive feedback accelerates the growth of the characteristic structure of the penitentes.

These icy statues are named after the spiked hats of the nazarenos, members of a brotherhood that participates in Easter processions around the world. It is not hard to picture them as an assembly of icy monks, congregating in the moonlight.

The image was taken by the side of the road that leads to ALMA. The observatory, which started Early Science operations on 30 September 2011, will eventually consist of 66 high-precision antennas operating together as a single giant telescope.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• More about ALMA
• More about penitentes
• ESO Photo Ambassadors

#L

This picture shows one of ESO’s Very Large Telescope (VLT) Unit Telescopes (UT4) whilst it was recently briefly held prisoner by ESO’s engineers. It was surrounded by a temporary cage of scaffolding as part of the preparations for the new Adaptive Optics Facility (AOF). This project will convert UT4 into a fully adaptive telescope. The AOF will correct for the blurring effects of the Earth’s atmosphere and will allow much sharper images to be achieved with the HAWK-I and MUSE instruments.

Many new components are being added to UT4 as part of the AOF. Among these is the deformable secondary mirror (DSM):  a thin-shell mirror, 1.1 metres in diameter, but just 2 millimetres thick. This mirror is thin enough to be easily deformed by more than a thousand actuators, up to a thousand times per second in order to counteract the atmosphere’s distortions. The DSM is the largest adaptive mirror manufactured to date (ann12015). Another vital element is the four Laser Guide Star Facility (4LGSF) — four special telescopes that fire laser beams high into the atmosphere to create artificial stars [1] (ann12012). Finally, the GRAAL and GALACSI adaptive optics modules will be responsible for analysing the light coming back from the laser guide stars.

This picture shows an ESO engineer supervising the work performed on UT4. To allow full access to the telescope, the cell of the primary mirror has been temporarily removed. Cables and pipes have also been removed and new ones have been installed. Mounting brackets have been added in preparation for the installation of the 4LGSF electronic cabinets and launch telescopes.

Notes

[1] The laser beams excite a layer of sodium atoms at an altitude of 90 kilometres in the atmosphere, making them glow as artificial stars.

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into its history. Once a month during 2012, a special Then and Now Picture of the Week shows how things have changed over the decades at the La Silla and Paranal observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

These two photographs were taken on the highest peak of La Silla, a mountain with an altitude of 2400 metres, at the edge of the Chilean Atacama Desert. La Silla was ESO’s first observatory site. The historical photograph, taken in 1975, shows some of the trucks and other equipment used for the construction of the dome of the ESO 3.6-metre telescope, which was underway behind the photographer. On the left are the water tanks for the site.

In the modern-day photograph, three new telescopes have appeared, all looking very different from each other. To the right of the water tanks is the ESO New Technology Telescope (NTT), which had its first light on 23 March 1989. This 3.58-metre telescope was the first ever to have a computer-controlled main mirror, which could adjust its shape during observations to optimise image quality. The octagonal enclosure housing the NTT is another technological breakthrough, ventilated by a system of flaps that makes air flow smoothly across the mirror, reducing turbulence and leading to sharper images.

To the right of the NTT is the Swiss 1.2-metre Leonhard Euler Telescope, which has a more traditional dome-shaped enclosure. It is operated by the Geneva Observatory at the Université de Genève in Switzerland, and had its first light on 12 April 1998. It is used to search for exoplanets in the southern sky; with its first discovery being a planet in orbit around the star Gliese 86 (see eso9855). The telescope also observes variable stars, gamma-ray bursts and active galactic nuclei.

In the foreground on the right is a building nicknamed the sarcofago (sarcophagus). This houses the TAROT (Télescope à Action Rapide pour les Objets Transitoires, or Rapid Action Telescope for Transient Objects), which started work at La Silla on 15 September 2006. This fast moving, relatively tiny 25-centimetre robotic telescope reacts extremely quickly to alerts from satellites about gamma-ray bursts, to pinpoint the positions of these dramatic but fleeting events. Observing these cosmic explosions lets astronomers study the formation of black holes and the evolution of stars in the early Universe. TAROT is operated by a consortium led by Michel Boër from Observatoire de Haute Provence in France.

The NTT is operated by ESO, while the Leonhard Euler Telescope and TAROT are among the national and project telescopes hosted at La Silla. Even today, over 40 years after its inauguration, La Silla remains at the forefront of astronomy.

Links

• The historical image
• The present-day image
• Side-by-side composite of the historical and present-day images
• More about La Silla
• Press release on the occasion of the 40th anniversary, in 2009, of La Silla’s inauguration
• ESO timeline

The otherworldly beauty of Chile’s Atacama Desert, home of ESO’s Very Large Telescope (VLT), stretches to the horizon in this panorama. On Cerro Paranal, the highest peak in the centre of this image, are the four giant Unit Telescopes of the VLT, each of which has a mirror with a diameter of 8.2 metres. On the peak to the left of Cerro Paranal is the VISTA survey telescope. This 4.1-metre telescope surveys broad swathes of the heavens, searching for interesting targets which the VLT, as well as other telescopes on the ground and in space, will study in greater detail.

This region offers some of the best conditions for viewing the night sky found anywhere on our planet. On the right of this 360-degree panorama, the Sun is setting over the Pacific Ocean, throwing long shadows across the mountainscape. On the left, the Moon gleams in the sky. Soon, the night’s observations will begin.

This wonderful panorama was made by Serge Brunier, an ESO Photo Ambassador. It is one of many awe-inspiring images in which he captures ESO’s observatories, their beautiful locations, and the splendour of the skies above them.

Links

• ESO Photo Ambassadors

ESO Photo Ambassador Stéphane Guisard captured this astounding panorama from the site of ALMA, the Atacama Large Millimeter/submillimeter Array, in the Chilean Andes. The 5000-metre-high and extremely dry Chajnantor plateau offers the perfect place for this state-of-the-art telescope, which studies the Universe in millimetre- and submillimetre-wavelength light.

Numerous giant antennas dominate the centre of the image. When ALMA is complete, it will have a total of 54 of these 12-metre-diameter dishes. Above the array, the arc of the Milky Way serves as a resplendent backdrop. When the panorama was taken, the Moon was lying close to the centre of the Milky Way in the sky, its light bathing the antennas in an eerie night-time glow. The Large and Small Magellanic Clouds, the biggest of the Milky Way's dwarf satellite galaxies, appear as two luminous smudges in the sky on the left. A particularly bright meteor streak gleams near the Small Magellanic Cloud.

On the right, some of ALMA’s smaller 7-metre antennas — twelve of which will be used to form the Atacama Compact Array — can be seen. Still further on the right shine the lights of the Array Operations Site Technical Building. And finally, looming behind this building is the dark, mountainous peak of Cerro Chajnantor.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• ESO Photo Ambassadors
• More about ALMA at ESO
• The Joint ALMA Observatory

The Atacama Pathfinder Experiment (APEX) telescope looks skyward during a bright, moonlit night on Chajnantor, one of the highest and driest observatory sites in the world. Astronomical treasures fill the sky above the telescope, a testament to the excellent conditions offered by this site in Chile’s Atacama region.

On the left shine the stars that make up the tail of the constellation of Scorpius (The Scorpion). The scorpion’s “stinger” is represented by the two bright stars that are particularly close to each other. Reaching across the sky and looking like a band of faint, glowing clouds is the plane of the Milky Way.

Between Scorpius and the next constellation to the right, Sagittarius (The Archer), which looms over APEX’s dish, a sparkling cluster of stars can be clearly seen. This is the open cluster Messier 7, also known as Ptolemy’s Cluster. Below Messier 7 and slightly to the right is the Butterfly Cluster, Messier 6. Further to the right, just above the edge of APEX’s dish, is a faint cloud which looks like a bright smudge. This is the famous Lagoon Nebula (see eso0936 for a closer view).

With a primary dish diameter of 12 metres, APEX is the largest single-dish submillimetre-wavelength telescope operating in the southern hemisphere. As the telescope’s name suggests, it is blazing a trail for the biggest submillimetre observatory in the world, the Atacama Large Millimeter/submillimeter Array (ALMA), which will be completed in 2013 (eso1137). APEX will share space with the 66 antennas of ALMA on the 5000-metre-high Chajnantor plateau in Chile. The APEX telescope is based on a prototype antenna constructed for the ALMA project, and it will find many targets that ALMA will be able to study in great detail.

ESO Photo Ambassador Babak Tafreshi made this panorama using a telephoto lens. Babak is also the founder of The World At Night, a programme to create and exhibit a collection of stunning photographs and time-lapse videos of the world’s most beautiful and historic sites against a nighttime backdrop of stars, planets and celestial events.

More information

APEX is a collaboration between the Max-Planck-Institut für Radioastronomie (MPIfR), the Onsala Space Observatory (OSO), and ESO, with operations of the telescope entrusted to ESO.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• Information about APEX
• ESO Photo Ambassadors

#L

Although Cerro Chico reaches the remarkable altitude of 5300 metres above sea level, it is only a small mountain in the majestic landscape of the Andean plateaux. Indeed, its own name means simply “small mountain” in Spanish. However, due to its position on the plateau of Chajnantor, the top of Cerro Chico offers an excellent and relatively easy-to-reach vantage point from which to enjoy this stunning view.

This 360-degree panoramic picture is centred on the northeast, where the highest volcanoes — most of them above 5500 metres — are seen. In the centre is Cerro Chajnantor itself. To the right, on the plateau, is the Atacama Pathfinder Experiment (APEX) telescope with Cerro Chascon behind it.  Further to the right, to the southeast, the Chajnantor plateau is almost fully visible. In addition to the APEX telescope, three Atacama Large Millimeter/submillimeter Array (ALMA) antennas can be seen, on the right. Many more have been added since this panorama was taken.

On the left of Cerro Chajnantor is Cerro Toco. Further to the left, in the northwest, we can see the distinctive conical shape of Licancabur volcano.

On the Chajnantor plateau, at 5000 metres altitude, the air is so thin and dry that it seems never to fill one’s lungs. Thanks to these extreme conditions, the millimetre and submillimetre radiation coming from the rest of the Universe can pass through what remains of the Earth’s atmosphere above the site, and can be detected from the ground with suitably sensitive telescopes such as ALMA and APEX.

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.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• This panorama, and others, can be seen as part of a stunning virtual tour of Chajnantor
• More ESO virtual tours

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

This historical image was taken around 1970 from the La Silla dormitories, located lower on the mountain than the telescope domes. The photo looks up towards the highest point of the mountain, on the left. The metallic structure visible near the top of this peak is not a telescope, but a water tank for the site. The white dome in the centre of the image is that of the ESO 1-metre Schmidt telescope, which started work in February 1972. On the far right of the image is the ESO 1-metre telescope, just visible over the ridge, and to the left of that one can just see the top of the Grand Prisme Objectif telescope.

In the present-day photograph, the dormitory buildings remain, but more have been built over the decades. The most striking changes, though, are visible around La Silla’s peak on the left. At the highest point is the ESO 3.6-metre telescope, which started operating in November 1976 and is still in use today. The 3.6-metre is home to HARPS, the foremost exoplanet hunter (see eso1134 and eso1214 for some recent results). The 3.6-metre, planned from the inception of ESO, was to crown the La Silla Observatory as its biggest telescope, and was a major engineering feat of its time. The smaller dome visible in front of the 3.6-metre is the 1.4-metre Coudé Auxiliary Telescope, which complemented its bigger neighbour.

To the right of the 3.6-metre is the 3.58-metre New Technology Telescope (NTT), recognisable by the angular, metallic appearance of its enclosure. The NTT, which started operating in March 1989, was the first telescope in the world to use a computer-controlled mirror. It was used as a precursor for the Very Large Telescope, to test many new technologies that were then used in the later telescope.

Other new sights in the modern-day photograph are the workshop building below the water tanks, and the Differential Image Motion Monitor (DIMM), used to measure the atmospheric seeing, located on stilts between the workshop and the ESO 1-metre Schmidt telescope.

Even today, La Silla remains a very active observatory where important discoveries are made. Both the NTT and the 3.6-metre telescope provided vital data which led to the discovery of the accelerating expansion of the Universe — a discovery for which the 2011 Nobel Prize in Physics was awarded.

Links

• The historical image
• The present-day image
• Side-by-side composite of the historical and present-day images
• More about La Silla
• Press release on the occasion of the 40th anniversary, in 2009, of La Silla’s inauguration
• ESO timeline

French photographer Serge Brunier — one of ESO’s Photo Ambassadors — has created this seamless 360-degree panorama of the Chajnantor plateau in the Atacama Desert, where the Atacama Large Millimeter/submillimeter Array (ALMA) is under construction.

The panorama projection has slightly warped the shapes of the ALMA antennas, but it still gives a sense of what it would be like to stand in the middle of this impressive new observatory. The 360-degree view also demonstrates the complete isolation of the Chajnantor plateau; at an altitude of 5000 metres, the backdrop is almost featureless, except for a few mountain peaks and hilltops.

Although constructing such an ambitious telescope project in a remote and harsh environment is challenging, the high altitude location is perfect for submillimetre astronomy.  That’s because water vapour in the atmosphere absorbs this type of radiation, but the air is much drier at high altitude sites such as Chajnantor.

ALMA started its first scientific observations on 30 September 2011 with a partial array of antennas. When the observatory is completed, the impressive sight of fifty 12-metre antennas — as well as a smaller array of four 12-metre and twelve 7-metre antennas, known as the Atacama Compact Array (ACA) — will make the isolated landscape seem slightly less empty. In the meantime, photographs like this one are documenting the progress of a new world-class telescope facility.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• ESO Photo Ambassadors
• For more information about ALMA at ESO
• The Joint ALMA Observatory website

The Very Large Telescope has captured another member of the Leo I group of galaxies, in the constellation of Leo (The Lion). The galaxy Messier 95 stands boldly face-on, offering an ideal view of its spiral structure. The spiral arms form an almost perfect circle around the galactic centre before they spread out, creating a mane-like effect of which any lion would be proud.

Another, perhaps even more striking, feature of Messier 95 is its blazing golden core. It contains a nuclear star-forming ring, almost 2000 light-years across, where a large proportion of the galaxy’s star formation takes place. This phenomenon occurs mostly in barred spiral galaxies such as Messier 95 and our home, the Milky Way.

In the Leo I group, Messier 95 is outshone by its brother Messier 96 (see potw1143). Messier 96 is in fact the brightest member of the group and — as “leader of the pride” — also gives Leo I its alternative name of the M 96 group. Nevertheless, Messier 95 also makes for a spectacular image.

Stop press! By coincidence Messier 95 is the host of a probable supernova that was first spotted on 17 March 2012. Discovery details are here. And as another coincidence both supernova and galaxy are currently very close to the brilliant planet Mars amongst the stars of Leo. Please note that the observations used to make this Picture of the Week were taken before the supernova occurred, and therefore the supernova itself does not appear in this image.

The domes of ESO’s Very Large Telescope sit atop Cerro Paranal, basking in the sunlight of another glorious cloudless day. But something is different about this picture: a fine layer of snow has settled across the desert landscape. This isn’t something you see every day: quite the opposite in fact, as the Atacama Desert gets almost no precipitation.

Several factors contribute to the dry conditions in the Atacama. The Andes mountain range blocks rain from the east, and the Chilean Coast Range from the west. The cold offshore Humboldt current in the Pacific Ocean creates a coastal inversion layer of cool air, which prevents rain clouds from developing. A region of high pressure in the south-eastern Pacific Ocean creates circulating winds, forming an anticyclone, which also helps to keep the climate of the Atacama dry. Thanks to all these factors, the region is widely regarded as the driest place on Earth!

At Paranal, the precipitation levels are usually just a few millimetres per year, with the humidity often dropping below 10%, and temperatures ranging from -8 to 25 degrees Celsius. The dry conditions in the Atacama Desert are a major reason why ESO chose it, and Cerro Paranal, to host the Very Large Telescope. While the very occasional snowfall may temporarily disrupt the dry conditions here, it does at least produce unusual views of rare beauty.

This photograph was taken by ESO Photo Ambassador Stéphane Guisard on 1 August 2011.

Links

• ESO Photo Ambassadors

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special “Then and Now” comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Here are two photographs of La Silla, taken in June 1968 and the present day from near the observatory’s water tanks, looking over the rest of the site. You can examine the changes with our mouseover image comparison.

In the historical image, the provisional residential area is visible in the foreground. The three telescopes in the background are, from left to right, the Grand Prism Objectif (GPO, first light in 1968), the ESO 1-metre telescope (first light in 1966), and the ESO 1.5-metre telescope (first light in 1968). These three telescopes were the first at La Silla. The white dome closest to the viewer is the ESO 1-metre Schmidt telescope, which began work in 1971.

Today, these four domes are still present, but the first three telescopes have been decommissioned. The ESO 1-metre Schmidt is still in operation, but is now a project telescope dedicated to the LaSilla–QUEST Variability survey (see potw1201a).

The present-day photograph also shows two new telescopes. The silver dome is that of the MPG/ESO 2.2-metre telescope, which has been in operation since early 1984 and is on indefinite loan to ESO from the Max-Planck-Gesellschaft. On the far left is the Danish 1.54-metre telescope, in use since 1979, which is one of several national telescopes at La Silla.

Links

• More about La Silla
• Press release on the occasion of the 40th anniversary, in 2009, of La Silla’s inauguration
• ESO timeline

The dynamism of ESO's Very Large Telescope in operation is wonderfully encapsulated in this unusual photograph, taken just after sunset at the moment Unit Telescope 1 starts work. An extended exposure time of 26 seconds has allowed ESO Photo Ambassador Gerhard Hüdepohl to record the movement of the dome, looking out through the opening from within, as the system swings into action. The rotating walls of the dome look like an ethereal swirl through which a slice of the Atacama Desert can be glimpsed, while the crisp dusk sky provides a splash of cool blue.

The telescope structure, seen stationary in the centre of the image, houses a mirror 8.2 metres in diameter, designed to collect light from the far reaches of our Universe. The dome itself is also an engineering marvel, moving with extreme precision and allowing for careful temperature control lest warm air currents disrupt observations.

Links

• ESO Photo Ambassadors

ESO’s Paranal Observatory facilities, such as the Residencia, give people who work at the site a welcome shelter from the surrounding inhospitable environment. In spite of that, they also offer interesting options for those who wish to enjoy the stark and silent beauty of the Atacama Desert. See this stunning panorama!

Among these is the Star Track, a walking path which connects the Residencia with the Very Large Telescope (VLT) platform, on the 2600-metre summit of Cerro Paranal. Built in 2001, the Star Track covers about two kilometres in distance and a difference in height of 200 metres. The last part of the track snakes around the west side of the mountain, offering incomparable views.

This 360-degree panoramic picture is centred facing north, so the right and left edges of the picture correspond to the south. To the north, the VLT control room and part of one of the Unit Telescope enclosures can just be seen peeking over a local bump in the terrain that hides most of the Paranal summit. To the west, clouds cover the Pacific Ocean, only 12 kilometres away. To the east, the facade and dome of the Residencia can be seen in the distance.

Links

• This panorama, and others, can be seen as part of a stunning virtual tour of Paranal and Armazones, at: http://www.eso.org/public/outreach/products/virtualtours/armazones.html
• More ESO virtual tours are available at: http://www.eso.org/public/outreach/products/virtualtours/

There is a lot to love about astronomy, and — in time for Valentine's Day — photographer Julien Girard offers a "heartfelt” example in this image. A bright pink symbol of love appears to float ethereally against the backdrop of the night sky over ESO's Paranal Observatory in northern Chile. Girard drew the heart in the air by shining a tiny flashlight keychain at the camera during a 25-second exposure with a tripod.

The central region of the Milky Way appears in the middle of the heart, as the plane of our galaxy stretches across the image. The stars of the constellation of Corona Australis (The Southern Crown) form a glittering arc of jewels at the top of the heart's left lobe. The diffuse glow to the left of the heart's lowest point is zodiacal light, caused by the scattering of light from the Sun by dust particles in the Solar System.

On the far right horizon, the 8.2-metre telescopes of the ESO Very Large Telescope (VLT) facility stand out in silhouette atop Cerro Paranal. The lights of a car driving down from the observatory platform can be seen just to the left of the telescopes.

Julien Girard is an ESO astronomer based in Chile, who works at the VLT. He is the instrument scientist for the NACO adaptive optics instrument on the VLT’s Unit Telescope 4. He submitted this photograph to the Your ESO Pictures Flickr group, from where it was picked out as an ESO Picture of the Week.

Links

• This photograph, with annotations, on Julien Girard’s Flickr photostream
• Julien Girard’s Flickr photostream
• Your ESO Pictures Flickr group

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into its history. Once a month during 2012, a special “Then and Now” comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

These two photographs show the La Silla Observatory in the late 1960s and the present day. You can also examine the differences between the two photographs with our mouseover comparison. The telescopes aren’t the only things that have changed; the cars in the photos also show the passing of time. The Volkswagen 1600 Variant in the first picture has been replaced in the second picture by a Suzuki 4WD. Nowadays, all ESO vehicles on La Silla are white, to improve visibility at night.

Standing alone in the centre of the historical image is the ESO 1-metre Schmidt telescope, which began work in 1971. Back then, it used photographic plates to take wide-field images of the southern sky four degrees across — large enough to fit the full Moon 64 times over. The huts lining the road to the right of the image are where astronomers used to sleep.

Fast forward to 2011 and another two telescopes appear. On the left is the MPG/ESO 2.2-metre telescope, which has been in operation since 1984. In fact, its construction is why the modern-day photograph could not be taken from exactly the same place! On the peak to the right is the New Technology Telescope (NTT) commissioned later in 1989. Both these telescopes have had enormous successes over the years and are still in operation today. And the huts for the astronomers have in the meantime been replaced with a more comfortable “hotel” on the edge of the site.

As for the Schmidt telescope, still standing in the middle, its original photographic camera was decommissioned in December 1998, but it lives on as a project telescope. It is being used to conduct the LaSilla–QUEST Variability survey: a search for so-called transient objects in the southern sky, such as new Pluto-sized dwarf planets, or supernovae. Its new camera has a mosaic of 112 CCDs, with a total of 160 million pixels — an excellent example of how modern technology can give an old telescope a new lease of life!

Links

• The historical image
• The present day image
• More about La Silla
• Press release on the occasion of the 40th anniversary, in 2009, of La Silla’s inauguration
• ESO timeline

In this photograph, taken by ESO Photo Ambassador Gianluca Lombardi, the Sun is rising and bathing the Chilean Atacama Desert in a familiar soft reddish glow. But this image, from 13 July 2011, has also captured something out of the ordinary: a dark shadow lurking on the horizon.

Gianluca took this photograph from Cerro Armazones, looking west. Armazones is the future home of the world’s biggest eye on the sky: the upcoming European Extremely Large Telescope (E-ELT). The Sun rose behind Gianluca in just the right place to cast a daunting shadow of the 3060-metre-high mountain onto the Earth’s atmosphere in the distance. The shadow can be seen reaching over the vast desert landscape, and up across the horizon on the left side of the image.

The bright summit visible on the right of the image is Cerro Paranal, at an altitude of 2600 metres. It is only 20 kilometres from Cerro Armazones, and is the home of ESO’s Very Large Telescope. Both sites have exceptional astronomical observing conditions. To its right is the adjacent peak where the VISTA survey telescope is located and to its left, on the horizon, are the Paranal Observatory’s basecamp and Residencia.

The white road winding across the bottom-left corner of the photograph is the route to the summit of Cerro Armazones.

Links

• This image, as well as many more stunning shots from Gianluca Lombardi, can be found on his Flickr photostream.
• Find out more about the ESO Photo Ambassadors here.
• Find out more about Cerro Armazones and the E-ELT here.

This image shows the swirling shape of galaxy NGC 2217, in the constellation of Canis Major (The Great Dog). In the central region of the galaxy is a distinctive bar of stars within an oval ring. Further out, a set of tightly wound spiral arms almost form a circular ring around the galaxy. NGC 2217 is therefore classified as a barred spiral galaxy, and its circular appearance indicates that we see it nearly face-on.

The outer spiral arms have a bluish colour, indicating the presence of hot, luminous, young stars, born out of clouds of interstellar gas. The central bulge and bar are yellower in appearance, due to the presence of older stars. Dark streaks can also be seen in places against the galaxy’s arms and central bulge, where lanes of cosmic dust block out some of the starlight.

The majority of spiral galaxies in the local Universe — including our own Milky Way — are thought to have a bar of some kind, and these structures play an important role in the development of a galaxy. They can, for example, funnel gas towards the centre of the galaxy, helping to feed a central black hole, or to form new stars.

Workers on the Atacama Large Millimeter/submillimeter Array (ALMA) project stand next to three of the telescope’s antennas. This photograph gives a real sense of the scale of the giant dishes, whose 12-metre diameters are about seven times the average human height. When completed, ALMA will consist of 66 high-precision antennas, 54 of them with 12-metre dishes as seen in this image, and 12 more compact ones with diameters of 7 metres. The yellow 28-wheel transporter vehicle, which has to be powerful enough to carry the 100-tonne antennas, is built on a similarly giant scale.

This photograph was taken at the 2900-metre-high ALMA Operations Support Facility in the foothills of the Chilean Andes, where the antennas are assembled and tested. On the left is one of the European ALMA antennas, pointing at the horizon. Behind it is one of the antennas provided to the project by Japan, while on the right, on the transporter vehicle and pointing upwards, is another European antenna. This is the first European antenna starting its journey up to the Array Operations Site on the Chajnantor plateau, photographed in July 2011 (see eso1127). Since this photograph was taken, the antennas, and others like them, have been put into operation on Chajnantor as ALMA has made its first scientific observations (see eso1137). ALMA is designed to study the cool Universe — the relic radiation of the Big Bang and the molecular gas and dust from which stars, planets and galaxies originate.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Twenty-five European ALMA antennas are being provided by ESO through a contract with the European AEM Consortium. ALMA will also have 25 antennas provided by North America, and 16 by East Asia.

The picture is part of the COMBO-17 survey (Classifying Objects by Medium-Band Observations in 17 Filters), a project dedicated to recording detailed images of small patches of the sky through filters of 17 different colours. The area covered in this image is only about the size of the full Moon, but thousands of galaxies can be identified just within this small region.

The image was taken with an exposure time of almost seven hours, which allowed the camera to capture the light from very faint and distant objects, as well as those that are closer to us. Galaxies with clear and regular structures, such as the spiral specimen viewed edge-on near the upper left corner, are only up to a few billion light-years away. The fainter, fuzzier objects are so far away that it has taken nine or ten billion years for their light to reach us.

The COMBO-17 survey is a powerful tool for studying the distribution of dark matter in galaxies. Dark matter is a mysterious substance that does not emit or absorb light and can only be detected by its gravitational pull on other objects. Some of the closer galaxies pictured act as lenses that distort the light coming from more distant galaxies placed along the same line of sight. By measuring this distortion, an effect known as gravitational lensing, astronomers are able to understand how dark matter is distributed in the objects that act as lenses.

The distortion is weak and, therefore, almost imperceptible to the human eye. However, because surveying the sky with 17 filters allows extremely precise distance measurements, it is possible to determine if two galaxies that appear to lie close to each other are actually at very different distances from the Earth. After identifying the galactic lensing systems, the distortion can be measured by averaging over thousands of galaxies. With more than 4000 galactic lenses identified, this COMBO-17 survey is an ideal method to help astronomers to understand the dark matter better.

This image was taken with three of the 17 filters from the project: B (blue), V (green), and R (red). Data through an additional near-infrared filter was also used. 

Links

• COMBO-17 at the Max Planck Institute for Astronomy

ESO turns 50 this year, and to celebrate this important anniversary, we will be showing you glimpses into our history. Once a month throughout 2012, a special “then and now” comparison Picture of the Week will show how things have changed over the decades at the La Silla and Paranal observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Our first stop on this journey through time is at La Silla, the first of ESO’s observatory sites. The historical image was taken in the late 1960s or early 1970s from the dome of the ESO 1.52-metre telescope, which had its first light in 1968. A second photograph, taken in the present day, shows how much the observatory has changed over the decades. You can examine the changes with our mouseover image comparison.

In the historical image, we can see the ESO 1-metre telescope in the foreground on the right, with the Grand Prism Objectif telescope (GPO) just peeking out from behind. The third telescope in this photo is the Schmidt 1-metre telescope, on the left. Behind it, at a higher level, are the water tanks of the observatory.

Moving through time to the present-day, we can see how much La Silla has evolved, with many more telescopes on the site. The ESO 3.6-metre telescope and the adjacent Coudé Auxiliary Telescope now stand out on the highest peak. The angular enclosure of the New Technology Telescope (NTT) is just to the left, next to the water tanks. The 15-metre-diameter dish of the Swedish–ESO Submillimetre Telescope (SEST) watches the horizon on the far right.

The new photograph was taken from a slightly different position on top of the ESO 1.52-metre telescope building, so the GPO is now hidden behind the ESO 1-metre telescope in the foreground. The white dome that is just visible behind the 1-metre is the Danish 1.54-metre telescope. In the centre of the photo we now see the silvery dome of the MPG/ESO 2.2-metre telescope.

Although some telescopes at La Silla, such as the ESO 1-metre and 1.52-metre, and the SEST, are no longer in operation, others are still doing front-line astronomy. The ESO 3.6-metre telescope hosts the HARPS instrument, the world’s leading exoplanet hunter (see eso1134 for some recent results). The NTT has been used to help explain the formation of massive stars (see eso1029). Both telescopes provided vital data which led to the discovery of the accelerating expansion of the Universe — a discovery for which the 2011 Nobel Prize in Physics was awarded. The MPG/ESO 2.2-metre telescope has also produced a treasure trove of data from breathtaking wide-field images to studies of gamma-ray bursts, the most explosive events in the Universe.

Links

• The historical image
• The present-day image
• Side-by-side composite of the historical and present-day images
• More about La Silla
• Press release on the occasion of the 40th anniversary, in 2009, of La Silla’s inauguration
• ESO timeline

As night was falling over ESO’s La Silla Observatory in Chile on 20 December 2009, the sky was not yet dark enough for the telescopes to start observations. But conditions were perfect to perform a clever trick with the dome of the Swiss 1.2-metre Leonhard Euler Telescope: allowing us to peer inside with this photograph apparently taken through the dome.

This image is a 75-second exposure taken while the slit of the Euler telescope’s dome was performing half a rotation at full speed. Through the ghostly blur of the moving dome walls, the telescope is clearly visible. A dim light was switched on in the interior of the building especially for the purpose of this photo.

The picture was taken by Malte Tewes, a young astronomer from the École Polytechnique Fédérale de Lausanne in Switzerland, who had just finished a two-week observing run at the telescope on the evening in question. The next observer, Amaury Triaud, and the telescope’s technician, Vincent Mégevand (both pictured), were on site so they could operate the dome from the inside while Malte took the photograph from outside.

The road that leads to ESO’s nearby 3.6-metre telescope is visible lined by a chain of lights to the left of the image. In addition to the 3.6-metre telescope, the New Technology Telescope, and the MPG/ESO 2.2-metre telescope, La Silla Observatory also hosts several national and project telescopes that are not operated by ESO. The Euler telescope, named after the famous Swiss mathematician Leonhard Euler, is one of them.

Links

• Malte Tewes' photostream on Flickr

Bathed in the pristine light of the Chilean Atacama Desert, the ESO VLT’s Auxiliary Telescope 2 stands on Cerro Paranal. It is one of four that are used with the Very Large Telescope Interferometer. During the day, its bulbous dome is closed, protecting the sensitive telescope within.

The magnificent 6739-metre volcano Llullaillaco stands proudly in the background of this photograph. Although it looks relatively close on the horizon, it is actually an incredible 190 kilometres away, on the border with Argentina. That Llullaillaco can be seen so clearly is evidence of the region’s unparallelled atmospheric conditions. The clear air is one of the many factors that make this such a wonderful location for astronomical observatories. It is from this excellent vantage point that ESO astronomers study objects that are not just hundreds of kilometres in the distance, but billions of light-years away.

This photograph was taken by ESO Photo Ambassador Gianluca Lombardi.

Links

• ESO Photo Ambassadors

This panoramic view of the Chajnantor plateau, spanning about 180 degrees from north (on the left) to south (on the right) shows the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) ranged across the unearthly landscape. Some familiar celestial objects can be seen in the night sky behind them. These crystal-clear night skies explain why Chile is the home of not only ALMA, but also several other astronomical observatories. This image is just part of an even wider panorama of Chajnantor.

In the foreground, the 12-metre diameter ALMA antennas are in action, working as one giant telescope, during the observatory’s first phase of scientific observations. On the far left, a cluster of smaller 7-metre antennas for ALMA’s compact array can be seen illuminated. The crescent Moon, although not visible in this image, casts stark shadows over all the antennas.

In the sky above the antennas, the most prominent bright “star” — on the left of the image — is in fact the planet Jupiter. The gas giant is the third brightest natural object in the night sky, after the Moon and Venus. The Large and Small Magellanic Clouds can also be clearly seen on the right of the image. The Large Magellanic Cloud looks like a puff of smoke, just above the rightmost antenna. The Small Magellanic Cloud is higher in the sky, towards the upper-right corner. Both “clouds” are in fact dwarf irregular galaxies, orbiting the Milky Way galaxy, at distances of about 160 000 and 200 000 light-years respectively.

On the far left of the panorama, just left of the foreground antennas, is the elongated smudge of the Andromeda galaxy. This galaxy, more than ten times further away than the Magellanic Clouds, is our closest major neighbouring galaxy. It is also the largest galaxy in the Local Group — the group of about 30 galaxies which includes our own — and contains approximately one trillion stars, more than twice as many as the Milky Way. It is the only major galaxy visible with the naked eye. Even though only its most central region is apparent in this image, the galaxy spans the equivalent of six full Moons in the sky.

This photograph was taken by Babak Tafreshi, the latest ESO Photo Ambassador. Babak is also founder of The World At Night, a programme to create and exhibit a collection of stunning photographs and time-lapse videos of the world’s most beautiful and historic sites against a nighttime backdrop of stars, planets and celestial events.

ALMA is being built on the Chajnantor plateau at an altitude of 5000 metres. The observatory, which started Early Science operations on 30 September 2011, will eventually consist of 66 antennas operating together as a single giant telescope. This international astronomy facility is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

• Time-lapse videos of ALMA on Chajnantor made by Babak Tafreshi: one, two
• ESO Photo Ambassadors
• More about ALMA at ESO: http://www.eso.org/public/teles-instr/alma.html
• The Joint ALMA Observatory: http://www.almaobservatory.org/
• The World At Night: http://www.twanight.org/

#L

This telescope is an important new component of the Four Laser Guide Star Facility, which will sharpen the already excellent vision of ESO’s Very Large Telescope (VLT). Four powerful 20-watt lasers, fired to an altitude of 90 kilometres up in the atmosphere, will help the VLT correct the image distortion caused by turbulence in the air. The Netherlands Organisation for Applied Scientific Research (TNO) is developing the launch telescopes through which the laser beams will be fired. The first of these laser launch telescopes — known as the Optical Tube Assembly — is seen here in the cleanroom at TNO’s Van Leeuwenhoek Laboratory in Delft, the Netherlands, having recently held its Acceptance Review. A special anti-reflective coating gives the lens on the telescope a distinctive blue hue. The photograph was taken by Fred Kamphues, who appears on the left. He is project manager for the Optical Tube Assembly, and is also a new ESO Photo Ambassador. On the right is system engineer Rens Henselmans.

The Four Laser Guide Star Facility is part of the next generation Adaptive Optics Facility, to be installed on the VLT’s 4th Unit Telescope, Yepun, in 2013. Adaptive optics systems rapidly adjust a deformable mirror to counteract the distorting effect of atmospheric turbulence — the same effect that makes stars twinkle — in real time. To do this, they use a guide star as a reference, since the star should appear as a sharp point when the effect of the atmosphere is removed. This lets the telescope make images almost as sharp as if it were in space.

ESO has led the way in adaptive optics systems, having used them for over 20 years on its telescopes. The first such system on the VLT was installed just over ten years ago (see eso0137). In early 2006, the technology was improved with the first use of a laser guide star at the VLT. The unit projects a high-power laser beam into the sky, which excites a layer of sodium atoms at an altitude of 90 kilometres in the atmosphere and makes them glow. This glowing spot acts as an artificial guide star which can be positioned at will in the sky, so astronomers are not restricted to observations close to a sufficiently bright natural guide star (eso0607).

The next generation Four Laser Guide Star Facility will use four such artificial stars, to improve the removal of atmospheric turbulence over a wider field of view. The technology will also serve as a testbed ahead of the construction of the future European Extremely Large Telescope, which will also have multiple laser guide star units.

Links

This image, from ESO’s Very Large Telescope (VLT), shows a truly remarkable galaxy known as NGC 3621. To begin with, it is a pure-disc galaxy. Like other spirals, it has a flat disc permeated by dark lanes of material and with prominent spiral arms where young stars are forming in clusters (the blue dots seen in the image). But while most spiral galaxies have a central bulge — a large group of old stars packed in a compact, spheroidal region — NGC 3621 doesn’t. In this image, it is clear that there is simply a brightening to the centre, but no actual bulge like the one in NGC 6744 (eso1118), for example.

NGC 3621 is also interesting as it is believed to have an active supermassive black hole at its centre that is engulfing matter and producing radiation. This is somewhat unusual because most of these so-called active galactic nuclei exist in galaxies with prominent bulges. In this particular case, the supermassive black hole is thought to have a relatively small mass, of around 20 000 times that of the Sun.

Another interesting feature is that there are also thought to be two smaller black holes, with masses of a few thousand times that of the Sun, near the nucleus of the galaxy. Therefore, NGC 3621 is an extremely interesting object which, despite not having a central bulge, has a system of three black holes in its central region.

This galaxy is located in the constellation of Hydra (The Sea Snake) and can be seen with a moderate-sized telescope. This image, taken using B, V, and I filters with the FORS1 instrument on the powerful VLT, shows striking detail in this odd object and also reveals a multitude of background galaxies. A number of bright foreground stars that belong to our own Milky Way are also visible.

At sunset, the sky is often painted with an array of oranges, reds and yellows, and even some shades of pink. There are, however, occasions when a green flash appears above the solar disc for a second or so. One such occurrence was captured beautifully in this picture taken from Cerro Paranal, a 2600-metre-high mountain in the Chilean Atacama Desert, by ESO Photo Ambassador Gianluca Lombardi. Cerro Paranal is home to ESO’s Very Large Telescope.

The green flash is a rather rare phenomenon; seeing such a transient event requires an unobstructed view of the setting (or rising) Sun and a very stable atmosphere. At Paranal the atmospheric conditions are just right for this, making the green flash a relatively common sight (see for example eso0812). But a double green flash such as this one is noteworthy even for Paranal.

The green flash occurs because the Earth’s atmosphere works like a giant prism that bends and disperses the sunlight. This effect is particularly significant at sunrise and sunset when the solar rays go through more of the lower, denser layers of the atmosphere. Shorter wavelength blue and green light from the Sun is bent more than longer wavelength orange and red, so it appears slightly higher in the sky than orange or red rays from the point of view of an observer.

When the Sun is close to the horizon and conditions are just right, a mirage effect related to the temperature gradient in the atmosphere can magnify the dispersion — the separation of colours — and produce the elusive green flash. A blue flash is almost never seen as the blue light is scattered by molecules and particles in the dense blanket of air towards the horizon.

The mirage can also distort the shape of the Sun and that of the flash. We see two bands of green light in this image because the weather conditions created two alternating cold and warm layers of air in the atmosphere.

This stunning photo was taken by ESO Photo Ambassador Gianluca Lombardi on 28 March 2011. The phenomenon was captured on camera as the Sun was setting on a sea of clouds below Cerro Paranal.

In the foothills of the Chilean Andes, at an altitude of 2900 metres, the Operations Support Facility (OSF) for the Atacama Large Millimeter/submillimeter Array (ALMA) is a hive of activity. This photograph shows engineers moving a heavyweight antenna at night — with the help of a special 28-wheel transporter — and illustrates how work at ALMA continues around the clock. The antenna, one of 25 provided for the ALMA project by ESO, is being moved into position next to antennas from the other ALMA partners to be tested and equipped with highly sensitive detectors.

When completed, ALMA will consist of 66 12-metre and 7-metre antennas that will work together as a giant radio telescope observing at millimetre and submillimetre wavelengths. The facility will allow astronomers to study our cosmic origins by probing the first stars and galaxies, and imaging the formation of planets.

The telescope is being constructed on Llano de Chajnantor, a plateau that is a 28-kilometre drive from the OSF, at the even higher altitude of 5000 metres. Since the photograph was taken, this antenna has joined others on Chajnantor and has been taking part in ALMA’s first science observations.

While the plateau’s elevated location gives it the extremely dry conditions that are vital for observing at millimetre and submillimetre wavelengths, the altitude make it less pleasant for people working there. Therefore, the people working on ALMA do as much as possible from the lower altitude of the OSF, where work continues day and night. Not only are astronomers and engineers working in shifts and controlling the telescope on Chajnantor remotely, but this is also where the antennas are assembled and tested, and where they are brought for occasional maintenance.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

This image shows some of the GRAAL instrument team, inspecting GRAAL’s mechanical assembly in the integration hall of ESO’s Headquarters in Garching bei Munchen, Germany. GRAAL, which will be installed on ESO’s Very Large Telescope (VLT) on Cerro Paranal in Chile, is designed to improve the vision of the VLT’s already excellent HAWK-I camera even further.

GRAAL stands for GRound layer Adaptive optics Assisted by Lasers. It will use the technique of adaptive optics to improve the quality of images by compensating for turbulence in the lower layers of the atmosphere, up to an altitude of 1 kilometre.

GRAAL will form part of the observatory’s next generation Adaptive Optics Facility (AOF). The VLT already uses a powerful laser beam to create an artificial guide star, 90 kilometres up in the atmosphere. The current adaptive optics systems use this guide star as a reference to remove the effect of turbulence in the atmosphere, giving sharper observations, almost as though the telescope were in space.

The next generation AOF, however, will have no fewer than four laser guide stars, launched from Yepun, the VLT’s fourth Unit Telescope. GRAAL captures their light with four sensors, and then adjusts the shape of a deformable mirror up to 1000 times per second to compensate for the blurring effect of the atmosphere. This mirror — part of the AOF upgrade — is in fact a complete replacement for the 1.1-metre secondary mirror of the telescope, and will be the largest deformable mirror yet made. Combined with the multiple guide stars of the laser launching facility, it allows for better corrections over a wider field of view.

GRAAL will be attached to the High Acuity Wide field K-band Imager (HAWK-I), already installed on Yepun. Currently, HAWK-I operates without adaptive optics. Installing GRAAL will improve the sharpness of HAWK-I’s images, and reduce the exposure times needed by up to a factor of two.

After recent successful testing of the main parts of its mechanical assembly, GRAAL’s optics are now being assembled at ESO’s Headquarters. The instrument is expected to reach Paranal at the end of 2013.

Links