Exploring the European Southern Observatory – 21st Century Astronomy 

A week ago, I got to view an extraordinary video, Extreme Astronomy, from the BBC.

You too can view it:

Please give this your best hour. I think you will be astonished. While Hubble and NASA’s SOFIA figure in this tale, its heart is the installations of the European Southern Observatory, which is not a thing or place, but an organization which builds and operates on the ground telescope installations that are as stunning in their power as NASA’s Hubble, Spitzer, Chandra, and, soon we hope, the James Webb, are in space.

The European Southern Observatory

“ESO is the pre-eminent intergovernmental science and technology organisation in astronomy. It carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities for astronomy to enable important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research.

ESO operates three unique world-class observing sites in the Atacama Desert region of Chile: La Silla, Paranal and Chajnantor. ESO’s first site is at La Silla, a 2400 m high mountain 600 km north of Santiago de Chile. It is equipped with several optical telescopes with mirror diameters of up to 3.6 metres. The 3.5-metre New Technology Telescope broke new ground for telescope engineering and design and was the first in the world to have a computer-controlled main mirror, a technology developed at ESO and now applied to most of the world’s current large telescopes. The ESO 3.6-metre telescope is now home to the world’s foremost extrasolar planet hunter: HARPS (High Accuracy Radial velocity Planet Searcher), a spectrograph with unrivalled precision.”

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Paranal Platform The VLT

The Very Large Telescope array (VLT) is the flagship facility for European ground-based astronomy at the beginning of the third Millennium. It is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors of 8.2m diameter and four movable 1.8m diameter Auxiliary Telescopes. The telescopes can work together, to form a giant ‘interferometer’, the ESO Very Large Telescope Interferometer, allowing astronomers to see details up to 25 times finer than with the individual telescopes. The light beams are combined in the VLTI using a complex system of mirrors in underground tunnels where the light paths must be kept equal to distances less than 1/1000 mm over a hundred metres. With this kind of precision the VLTI can reconstruct images with an angular resolution of milliarcseconds, equivalent to distinguishing the two headlights of a car at the distance of the Moon.

The 8.2m diameter Unit Telescopes can also be used individually. With one such telescope, images of celestial objects as faint as magnitude 30 can be obtained in a one-hour exposure. This corresponds to seeing objects that are four billion (four thousand million) times fainter than what can be seen with the unaided eye.”


La Silla

“The La Silla Observatory is located at the outskirts of the Chilean Atacama Desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres. Like other observatories in this geographical area, La Silla is located far from sources of light pollution and, like the Paranal Observatory, home to the Very Large Telescope, it has one of the darkest night skies on the Earth. La Silla has been an ESO stronghold since the 1960s. Here, ESO operates some of the most productive 4-metre class telescopes in the world.

The 3.58-metre New Technology Telescope (NTT) broke new ground for telescope engineering and design and was the first in the world to have a computer-controlled main mirror (active optics), a technology developed at ESO and now applied to most of the world’s current large telescopes.

The ESO 3.6-metre telescope is now home to the world’s foremost extrasolar planet hunter: HARPS (High Accuracy Radial velocity Planet Searcher), a spectrograph with unrivalled precision.

The La Silla Observatory is the first world-class observatory to have been granted certification for the International Organization for Standardization (ISO) 9001 Quality Management System. The infrastructure of La Silla is also used by many of the ESO member states for targeted projects such as the Swiss 1.2-metre Leonhard Euler telescope, the Rapid-Eye Mount (REM) and TAROT gamma-ray burst chaser, as well as more common user facilities such as the MPG/ESO 2.2-metre and the Danish 1.54-metre telescopes. The 67-million pixel Wide Field Imager on the 2.2-metre telescope has taken many amazing images of celestial objects, some of which have now become icons in their own right.”

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ALMA Atacama Large Millimeter/submillimeter Array

“High on the Chajnantor plateau in the Chilean Andes, the European Southern Observatory (ESO), together with its international partners, is building ALMA — a state-of-the-art telescope to study light from some of the coldest objects in the Universe. This light has wavelengths of around a millimetre, between infrared light and radio waves, and is therefore known as millimetre and submillimetre radiation. This is the largest ground-based astronomical project in existence.
What is submillimetre astronomy?

Light at these wavelengths comes from vast cold clouds in interstellar space, at temperatures only a few tens of degrees above absolute zero, and from some of the earliest and most distant galaxies in the Universe. Astronomers can use it to study the chemical and physical conditions in molecular clouds — the dense regions of gas and dust where new stars are being born. Often these regions of the Universe are dark and obscured in visible light, but they shine brightly in the millimetre and submillimetre part of the spectrum.
Why build ALMA in the high Andes?

Millimetre and submillimetre radiation opens a window into the enigmatic cold Universe, but the signals from space are heavily absorbed by water vapour in the Earth’s atmosphere. Telescopes for this kind of astronomy must be built on high, dry sites, such as the 5000-m high plateau at Chajnantor, one of the highest astronomical observatory sites on Earth.

The ALMA site, some 50 km east of San Pedro de Atacama in northern Chile, is in one of the driest places on Earth. Astronomers find unsurpassed conditions for observing, but they must operate a frontier observatory under very difficult conditions. Chajnantor is more than 750 m higher than the observatories on Mauna Kea, and 2400 m higher than the VLT on Cerro Paranal.”

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The European Extremely Large Telescope

“Extremely Large Telescopes are considered worldwide as one of the highest priorities in ground-based astronomy. They will vastly advance astrophysical knowledge, allowing detailed studies of subjects including planets around other stars, the first objects in the Universe, super-massive black holes, and the nature and distribution of the dark matter and dark energy which dominate the Universe.

Since the end of 2005 ESO has been working together with its user community of European astronomers and astrophysicists to define the new giant telescope needed by the middle of the next decade. More than 100 astronomers from all European countries have been involved throughout 2006, helping the ESO Project Offices to produce a novel concept, in which performance, cost, schedule and risk were carefully evaluated.

Dubbed E-ELT for European Extremely Large Telescope, this revolutionary new ground-based telescope concept will have a 40-metre-class main mirror and will be the largest optical/near-infrared telescope in the world: “the world’s biggest eye on the sky”.

With the start of operations planned for early in the next decade, the E-ELT will tackle the biggest scientific challenges of our time, and aim for a number of notable firsts, including tracking down Earth-like planets around other stars in the “habitable zones” where life could exist — one of the Holy Grails of modern observational astronomy. It will also perform “stellar archaeology” in nearby galaxies, as well as make fundamental contributions to cosmology by measuring the properties of the first stars and galaxies and probing the nature of dark matter and dark energy. On top of this astronomers are also planning for the unexpected — new and unforeseeable questions will surely arise from the new discoveries made with the E-ELT.”

In my view, what the ESO does on the ground is every bit as important and astonishing as what NASA does in space. In the video, near the end, scientists answer the obvious question: so, which is the best platform for 21st Cetury Astronomy? Space? Which telescope? Ground? Which telescope? The answer is that in order to arrive at the best and most complete record of what there is to find and see, astronomers must use all of the platforms, the very different from each other space telescopes, the ground based telescopes at their different altitudes and wavelength ranges.

Please watch the video and then please visit the ESO web site and its various specialized pages. You will be entranced.

ESO, the European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.