Comunicados de Prensa

28 de Abril de 2004: Stars like our Sun are members of galaxies, and most galaxies are themselves members of clusters of galaxies. In these, they move around among each other in a mostly slow and graceful ballet. But every now and then, two or more of the members may get too close for comfort - the movements become hectic, sometimes indeed dramatic, as when galaxies end up colliding.

14 de Abril de 2004: New images of unsurpassed clarity have been obtained with the ESO Very Large Telescope (VLT) of formations on the surface of Titan, the largest moon in the Saturnian system. They were made by an international research team [1] during recent commissioning observations with the "Simultaneous Differential Imager (SDI)", a novel optical device, just installed at the NACO Adaptive Optics instrument [2]. With the high-contrast SDI camera, it is possible to obtain extremely sharp images in three colours simultaneously. Although mainly conceived for exoplanet imaging, this device is also very useful for observations of objects with thick atmospheres in the solar system like Titan. Peering at the same time through a narrow, unobscured near-infrared spectral window in the dense methane atmosphere and an adjacent non-transparent waveband, images were obtained that are virtually uncontaminated by atmospheric components. They map the reflectivity of a large number of surface features in unprecedented detail. The images show a number of surface regions with very different reflectivity. Of particular interest are several large "dark" areas of uniformly low reflectivity. One possible interpretation is that they represent huge surface reservoirs of liquid hydrocarbons. Whatever the case, these new observations will be most useful for the planning of the delivery of the Huygens probe - now approaching the Saturn system on the NASA/ESA Cassini spacecraft and scheduled for descent to Titan's surface in early 2005.

6 de Abril de 2004: A team of astronomers from Denmark, Switzerland and Sweden [2] has achieved a major breakthrough in our understanding of the Milky Way, the galaxy in which we live. After more than 1,000 nights of observations spread over 15 years, they have determined the spatial motions of more than 14,000 solar-like stars residing in the neighbourhood of the Sun. For the first time, the changing dynamics of the Milky Way since its birth can now be studied in detail and with a stellar sample sufficiently large to allow a sound analysis. The astronomers find that our home galaxy has led a much more turbulent and chaotic life than previously assumed.

5 de Abril de 2004: Another vital step has been accomplished as planned towards full operation of the ESO Very Large Telescope Interferometer (VLTI) at the Paranal Observatory in Chile, one of the world's foremost astronomical facilities. In the night of March 20-21, 2004, a team of astronomers and engineers from France, Italy, Germany and ESO celebrated the successful assembly and completion of the first on-line tests of the latest of the first-generation VLTI instruments, the Astronomical Multiple BEam Recombiner (AMBER). They combined the two beams of light from the southern star Theta Centauri from two test telescopes ("siderostats" with 40-cm aperture) to produce strong and clear interferometric fringes. Equally successful observations were then obtained on the bright star Sirius, and consistently repeated during the following nights.

1 de Abril de 2004: One of the world's most advanced astronomical research facilities, the ESO Very Large Telescope (VLT) at the Paranal Observatory in the Chilean Atacama desert, celebrates an important anniversary today.

1 de Abril de 2004: Titan, the largest moon of Saturn was discovered by Dutch astronomer Christian Huygens in 1655 and certainly deserves its name. With a diameter of no less than 5,150 km, it is larger than Mercury and twice as large as Pluto. It is unique in having a hazy atmosphere of nitrogen, methane and oily hydrocarbons. Although it was explored in some detail by the NASA Voyager missions, many aspects of the atmosphere and surface still remain unknown. Thus, the existence of seasonal or diurnal phenomena, the presence of clouds, the surface composition and topography are still under debate. There have even been speculations that some kind of primitive life (now possibly extinct) may be found on Titan.

31 de Marzo de 2004: Detecting or constraining the possible time variations of fundamental physical constants is an important step toward a complete understanding of basic physics and hence the world in which we live. A step in which astrophysics proves most useful. Previous astronomical measurements of the fine structure constant - the dimensionless number that determines the strength of interactions between charged particles and electromagnetic fields - suggested that this particular constant is increasing very slightly with time. If confirmed, this would have very profound implications for our understanding of fundamental physics. New studies, conducted using the UVES spectrograph on Kueyen, one of the 8.2-m telescopes of ESO's Very Large Telescope array at Paranal (Chile), secured new data with unprecedented quality. These data, combined with a very careful analysis, have provided the strongest astronomical constraints to date on the possible variation of the fine structure constant. They show that, contrary to previous claims, no evidence exist for assuming a time variation of this fundamental constant.

2 de Marzo de 2004: In the morning of March 2, the Rosetta spacecraft was launched on board an Ariane-5 launcher from the European Spaceport in Kourou, French Guiana. The European Space Agency (ESA) spacecraft will be the first to land on a comet.

1 de Marzo de 2004: Using the ISAAC near-infrared instrument on ESO's Very Large Telescope, and the magnification effect of a gravitational lens, a team of French and Swiss astronomers [2] has found several faint galaxies believed to be the most remote known. Further spectroscopic studies of one of these candidates has provided a strong case for what is now the new record holder - and by far - of the most distant galaxy known in the Universe. Named Abell 1835 IR1916, the newly discovered galaxy has a redshift of 10 [3] and is located about 13,230 million light-years away. It is therefore seen at a time when the Universe was merely 470 million years young, that is, barely 3 percent of its current age. This primeval galaxy appears to be ten thousand times less massive than our Galaxy, the Milky Way. It might well be among the first class of objects which put an end to the Dark Ages of the Universe. This remarkable discovery illustrates the potential of large ground-based telescopes in the near-infrared domain for the exploration of the very early Universe.

16 de Febrero de 2004: On June 8, 2004, Venus - the Earth's sister planet - will pass in front of the Sun. This event, a 'transit', is extremely rare - the last one occurred in 1882, 122 years ago. Easily observable in Europe, Asia, Africa and Australia, it is likely to attract the attention of millions of people on these continents and, indeed, all over the world. On this important occasion, the European Southern Observatory (ESO) has joined forces with the European Association for Astronomy Education (EAAE), the Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE) and the Observatoire de Paris in France, as well as the Astronomical Institute of the Academy of Sciences of Czechia to establish the Venus Transit 2004 (VT-2004) public education programme. It is supported by the European Commission in the framework of the European Science and Technology Week and takes advantage of this extraordinary celestial event to expose the public - in a well-considered, interactive and exciting way - to a number of fundamental issues at the crucial interface between society and basic science. VT-2004 has several components, including an instructive and comprehensive website (www.vt-2004.org). It is directed towards the wide public in general and the media, school students and their teachers, as well as amateur astronomers in particular. It invites all interested persons to participate actively in the intercontinental VT-2004 Observing Campaign (that reenacts historical Venus Transit observations) and the VT-2004 Video Contest. During the VT-2004 Final Event in November, the winners of the Video Contest will be chosen by an international jury. This meeting will also serve to discuss the project and its impact.

9 de Febrero de 2004: Finland will become the eleventh member state of the European Southern Observatory (ESO) [1]. Today, during a ceremony at the ESO Headquarters in Garching (Germany), a corresponding Agreement was signed by the Finnish Minister of Education and Science, Ms. Tuula Haatainen and the ESO Director General, Dr. Catherine Cesarsky, in the presence of other high officials from Finland and the ESO member states (see Video Clip 02/04 below). Following subsequent ratification by the Finnish Parliament of the ESO Convention and the associated protocols [2], it is foreseen that Finland will formally join ESO on July 1, 2004.

30 de Enero de 2004: Another advanced astronomical telescope has just been installed at the Paranal Observatory, located in the heart of the Chilean Atacama Desert and home of the ESO Very Large Telescope (VLT). The new telescope, known as Auxiliary Telescope no. 1 (AT1), forms part of the VLT Interferometer (VLTI). It has a main mirror of 1.8-m diameter and is installed in a compact dome. In contrast to the four giant 8.2-m telescopes and, indeed, to any other telescope in the world of this size, it can be moved along a system of railway tracks on the top of the Paranal mountain. It sends the captured light from celestial objects into the subterranean Interferometric Tunnel from where it is directed to the central Interferometric Laboratory. This is the first of four AT's that will be installed in 2004-2006. These compact, high-tech telescopes are built by the AMOS company in Liège (Belgium). When placed in different configurations on the tracks, they will enable the VLTI to operate with great flexibility (also when the large telescopes are busy with other observations) and to obtain extremely sharp images of celestial objects - ultimately with a resolution that corresponds to seeing an astronaut on the Moon.

7 de Enero de 2004: Among the many astronomical highlights of 2003, the Transit of Mercury certainly attracted great attention as shown by the record number of hits the ESO web page received on that day. But this was a mere rehearsal of an even bigger event we will enjoy in 2004: the Venus Transit.

23 de Diciembre de 2003: A Happy New Year!

19 de Diciembre de 2003: An international team of astronomers [1] has determined the colour of the Universe when it was very young. While the Universe is now kind of beige, it was much bluer in the distant past , at a time when it was only 2,500 million years old. This is the outcome of an extensive and thorough analysis of more than 300 galaxies seen within a small southern sky area, the so-called Hubble Deep Field South. The main goal of this advanced study was to understand how the stellar content of the Universe was assembled and has changed over time. Dutch astronomer Marijn Franx , a team member from the Leiden Observatory (The Netherlands), explains: "The blue colour of the early Universe is caused by the predominantly blue light from young stars in the galaxies. The redder colour of the Universe today is caused by the relatively larger number of older, redder stars." The team leader, Gregory Rudnick from the Max-Planck Institut für Astrophysics (Garching, Germany) adds: "Since the total amount of light in the Universe in the past was about the same as today and a young blue star emits much more light than an old red star, there must have been significantly fewer stars in the young Universe than there is now. Our new findings imply that the majority of stars in the Universe were formed comparatively late, not so long before our Sun was born, at a moment when the Universe was around 7,000 million years old." These new results are based on unique data collected during more than 100 hours of observations with the ISAAC multi-mode instrument at ESO's Very Large Telescope (VLT), as part of a major research project, the Faint InfraRed Extragalactic Survey (FIRES) . The distances to the galaxies were estimated from their brightness in different optical near-infrared wavelength bands.

19 de Diciembre de 2003: Not so long ago, the real nature of the "spiral nebulae", spiral-shaped objects observed in the sky through telescopes, was still unknown. This long-standing issue was finally settled in 1924 when the famous American astronomer Edwin Hubble provided conclusive evidence that they are located outside our own galaxy and are in fact "island universes" of their own. Nowadays, we know that the Milky Way is just one of billions of galaxies in the Universe. They come in vastly different shapes - spiral, elliptical, irregular - and many of them are simply beautiful, especially the spiral ones. Astronomers Mark Neeser from the Universitäts-Sternwarte München (Germany) and Peter Barthel from the Kapteyn Institute in Groningen (The Netherlands) were clearly not insensitive to this when they obtained images of three beautiful spiral galaxies with ESO's Very Large Telescope (VLT). They did this in twilight during the early morning when they had to stop their normal observing programme, searching for very distant and faint quasars.

27 de Noviembre de 2003: On December 1 to 3, the city of Munich (Bavaria, Germany) will be the venue for a "Workshop on Large Scale Programmes and Projects in Astronomy and Astrophysics" organised by the Organisation for Economic Co-operation and Development (OECD) Global Science Forum in co-operation with the European Southern Observatory (ESO). The Workshop will be chaired by Ian Corbett (ESO).

18 de Noviembre de 2003: Ever since 1841, when the until then inconspicuous southern star Eta Carinae underwent a spectacular outburst, astronomers have wondered what exactly is going on in this unstable giant star. However, due to its considerable distance - 7,500 light-years - details of the star itself were beyond observation. This star is known to be surrounded by the Homunculus Nebula , two mushroom-shaped clouds ejected by the star, each of which is hundreds of times larger than our solar system. Now, for the first time, infrared interferometry with the VINCI instrument on ESO's Very Large Telescope Interferometer (VLTI) enabled an international team of astronomers [1] to zoom-in on the inner part of its stellar wind. For Roy van Boekel , leader of the team, these results indicate that " the wind of Eta Carinae turns out to be extremely elongated and the star itself is highly unstable because of its fast rotation."

12 de Noviembre de 2003: New observations of a Gamma-Ray Burst in polarised light, performed with the FORS instrument on ESO's Very Large Telescope, reveal for the first time a significant variation in time of the polarisation properties. This behaviour is unpredicted by major existing thoeries.

6 de Noviembre de 2003: Scientists and dignitaries from Europe, North America and Chile are breaking ground today (Thursday, November 6, 2003) on what will be the world's largest, most sensitive radio telescope operating at millimeter wavelengths. ALMA - the "Atacama Large Millimeter Array" - will be a single instrument composed of 64 high-precision antennas located in the II Region of Chile, in the District of San Pedro de Atacama, at the Chajnantor altiplano, 5,000 metres above sea level. ALMA 's primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimetre portion of the electromagnetic spectrum.