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20 December 2006: Nature has again thrown astronomers for a loop. Just when they thought they understood how gamma-ray bursts formed, they have uncovered what appears to be evidence for a new kind of cosmic explosion. These seem to arise when a newly born black hole swallows most of the matter from its doomed parent star.

31 August 2006: Astronomers, using ESO's Very Large Telescope, have for the first time made the link between an X-ray flash and a supernova. Such flashes are the little siblings of gamma-ray bursts (GRB) and this discovery suggests the existence of a population of events less luminous than 'classical' GRBs, but possibly much more numerous.

4 August 2006: The cast of exoplanets has an extraordinary new member. Using ESO's telescopes, astronomers have discovered an approximately seven-Jupiter-mass companion to an object that is itself only twice as hefty. Both objects have masses similar to those of extra-solar giant planets, but they are not in orbit around a star - instead they appear to circle each other. The existence of such a double system puts strong constraints on formation theories of free-floating planetary mass objects.

6 June 2006: Two new studies, based on observations made with ESO's telescopes, show that objects only a few times more massive than Jupiter are born with discs of dust and gas, the raw material for planet making. This suggests that miniature versions of the solar system may circle objects that are some 100 times less massive than our Sun.

4 November 2005: Image eso0535a shows in amazing details a group of galaxies known as Robert's Quartet [1]. The image is based on data collected with the FORS2 multi-mode instrument on ESO's Very Large Telescope.

6 October 2005: An international team of astronomers led by Danish astronomer Jens Hjorth [1] has for the first time observed the visible light from a short gamma-ray burst (GRB). Using the 1.5m Danish telescope at La Silla (Chile), they showed that these short, intense bursts of gamma-ray emission most likely originate from the violent collision of two merging neutron stars. The same team has also used ESO's Very Large Telescope to constrain the birthplace of the first ever short burst whose position could be pinpointed with high precision, GRB 050509B. The results are being published in the October 6 issue of the journal Nature. Gamma-ray bursts, the most powerful type of explosion known in the Universe, have been a mystery for three decades. They come in two different flavours, long and short ones. Over the past few years, international efforts have convincingly shown that long gamma-ray bursts are linked with the ultimate explosion of massive stars.

29 September 2005: Astronomers have released a new, stunning picture of the spiral galaxy NGC 1350. Resembling the shape of an eye, the galaxy exhibits a double ring structure whose blue glow reveals the presence of many young stars.

10 August 2005: How does the Galaxy in which we live look like? It is almost certain that we will never be able to send a probe out of our Milky Way to take a snapshot, in the same way as the first satellites could do to give us striking images of planet Earth. But astronomers do not need this to imagine what our bigger home resembles. And they have a pretty good idea of it.

30 June 2005: Using ESO's Very Large Telescope, Rémi Cabanac and his European colleagues have discovered an amazing cosmic mirage, known to scientists as an Einstein Ring. This cosmic mirage, dubbed FOR J0332-3557, is seen towards the southern constellation Fornax (the Furnace), and is remarkable on at least two counts. First, it is a bright, almost complete Einstein ring. Second, it is the farthest ever found.

2 March 2005: Combining observations with ESO's Very Large Telescope and ESA's XMM-Newton X-ray observatory, astronomers have discovered the most distant, very massive structure in the Universe known so far. It is a remote cluster of galaxies that is found to weigh as much as several thousand galaxies like our own Milky Way and is located no less than 9,000 million light-years away. The VLT images reveal that it contains reddish and elliptical, i.e. old, galaxies. Interestingly, the cluster itself appears to be in a very advanced state of development. It must therefore have formed when the Universe was less than one third of its present age. The discovery of such a complex and mature structure so early in the history of the Universe is highly surprising. Indeed, until recently it would even have been deemed impossible.

13 January 2005: Most present-day large galaxies are spirals, presenting a disc surrounding a central bulge. Famous examples are our own Milky Way or the Andromeda Galaxy. When and how did these spiral galaxies form? Why do a great majority of them present a massive central bulge? An international team of astronomers [1] presents new convincing answers to these fundamental questions. For this, they rely on an extensive dataset of observations of galaxies taken with several space- and ground-based telescopes. In particular, they used over a two-year period, several instruments on ESO's Very Large Telescope. Among others, their observations reveal that roughly half of the present-day stars were formed in the period between 8,000 million and 4,000 million years ago, mostly in episodic burst of intense star formation occurring in Luminous Infrared Galaxies. From this and other evidence, the astronomers devised an innovative scenario, dubbed the "spiral rebuilding". They claim that most present-day spiral galaxies are the results of one or several merger events. If confirmed, this new scenario could revolutionise the way astronomers think galaxies formed.

7 July 2004: Current theories of the formation of galaxies are based on the hierarchical merging of smaller entities into larger and larger structures, starting from about the size of a stellar globular cluster and ending with clusters of galaxies. According to this scenario, it is assumed that no massive galaxies existed in the young universe. However, this view may now have to be revised. Using the multi-mode FORS2 instrument on the Very Large Telescope at Paranal, a team of Italian astronomers [2] have identified four remote galaxies, several times more massive than the Milky Way galaxy, or as massive as the heaviest galaxies in the present-day universe. Those galaxies must have formed when the Universe was only about 2,000 million years old, that is some 12,000 million years ago. The newly discovered objects may be members of a population of old massive galaxies undetected until now. The existence of such systems shows that the build-up of massive elliptical galaxies was much faster in the early Universe than expected from current theory.

1 September 2003: Seventeen years after the last passage of Comet Halley, the ESO Very Large Telescope at Paranal (Chile) has captured a unique image of this famous object as it cruises through the outer solar system. It is completely inactive in this cold environment. No other comet has ever been observed this far - 4200 million km from the Sun - or that faint - nearly 1000 million times fainter than what can be perceived with the unaided eye. This observation is a byproduct of a dedicated search [1] for small Trans-Neptunian Objects, a population of icy bodies of which more than 600 have been found during the past decade.

21 August 2003: Using the ESO Very Large Telescope (VLT) , two astronomers from Germany and the UK [2] have discovered some of the most distant galaxies ever seen. They are located about 12,600 million light-years away. It has taken the light now recorded by the VLT about nine-tenths of the age of the Universe to traverse this huge distance. We therefore observe those galaxies as they were at a time when the Universe was very young, less than about 10% of its present age . At this time, the Universe was emerging from a long period known as the "Dark Ages," entering the luminous "Cosmic Renaissance" epoch. Unlike previous studies which resulted in the discovery of a few, widely dispersed galaxies at this early epoch, the present study found at least six remote citizens within a small sky area, less than five per cent the size of the full moon! This allowed understanding the evolution of these galaxies and how they affect the state of the Universe in its youth. In particular, the astronomers conclude on the basis of their unique data that there were considerably fewer luminous galaxies in the Universe at this early stage than 500 million years later. There must therefore be many less luminous galaxies in the region of space that they studied, too faint to be detected in this study. It must be those still unidentified galaxies that emit the majority of the energetic photons needed to ionise the hydrogen in the Universe at that particularly epoch.

14 July 2003: Using the ESA XMM-Newton satellite, a team of European and Chilean astronomers [2] has obtained the world's deepest "wide-field" X-ray image of the cosmos to date. This penetrating view, when complemented with observations by some of the largest and most efficient ground-based optical telescopes, including the ESO Very Large Telescope (VLT), has resulted in the discovery of several large clusters of galaxies. These early results from an ambitious research programme are extremely promising and pave the way for a very comprehensive and thorough census of clusters of galaxies at various epochs. Relying on the foremost astronomical technology and with an unequalled observational efficiency, this project is set to provide new insights into the structure and evolution of the distant Universe.

18 June 2003: A very bright burst of gamma-rays was observed on March 29, 2003 by NASA's High Energy Transient Explorer (HETE-II) , in a sky region within the constellation Leo. Within 90 min, a new, very bright light source (the "optical afterglow") was detected in the same direction by means of a 40-inch telescope at the Siding Spring Observatory (Australia) and also in Japan. The gamma-ray burst was designated GRB 030329 , according to the date. And within 24 hours, a first, very detailed spectrum of this new object was obtained by the UVES high-dispersion spectrograph on the 8.2-m VLT KUEYEN telescope at the ESO Paranal Observatory (Chile). It allowed to determine the distance as about 2,650 million light-years (redshift 0.1685). Continued observations with the FORS1 and FORS2 multi-mode instruments on the VLT during the following month allowed an international team of astronomers [1] to document in unprecedented detail the changes in the spectrum of the optical afterglow of this gamma-ray burst . Their detailed report appears in the June 19 issue of the research journal "Nature". The spectra show the gradual and clear emergence of a supernova spectrum of the most energetic class known, a "hypernova" . This is caused by the explosion of a very heavy star - presumably over 25 times heavier than the Sun. The measured expansion velocity (in excess of 30,000 km/sec) and the total energy released were exceptionally high, even within the elect hypernova class. From a comparison with more nearby hypernovae, the astronomers are able to fix with good accuracy the moment of the stellar explosion. It turns out to be within an interval of plus/minus two days of the gamma-ray burst. This unique conclusion provides compelling evidence that the two events are directly connected. These observations therefore indicate a common physical process behind the hypernova explosion and the associated emission of strong gamma-ray radiation. The team concludes that it is likely to be due to the nearly instantaneous, non-symmetrical collapse of the inner region of a highly developed star (known as the "collapsar" model). The March 29 gamma-ray burst will pass into the annals of astrophysics as a rare "type-defining event", providing conclusive evidence of a direct link between cosmological gamma-ray bursts and explosions of very massive stars.

28 May 2003: With improved telescopes and instruments, observations of extremely remote and faint galaxies have become possible that were until recently astronomers' dreams. One such object was found by a team of astronomers [2] with a wide-field camera installed at the Canada-France-Hawaii telescope at Mauna Kea (Hawaii, USA) during a search for extremely distant galaxies. Designated "z6VDF J022803-041618" , it was detected because of its unusual colour , being visible only on images obtained through a special optical filter isolating light in a narrow near-infrared band. A follow-up spectrum of this object with the FORS2 multi-mode instrument at the ESO Very Large Telescope (VLT) confirmed that it is a very distant galaxy (the redshift is 6.17 [3]). It is seen as it was when the Universe was only about 900 million years old. z6VDF J022803-041618 is one of the most distant galaxies for which spectra have been obtained so far. Interestingly, it was discovered because of the light emitted by its massive stars and not, as originally expected, from emission by hydrogen gas.

16 January 2003: At a distance of some 50 million light-years, the Virgo Cluster is the nearest galaxy cluster. It is located in the zodiacal constellation of the same name (The Virgin) and is a large and dense assembly of hundreds of galaxies. The "intracluster" space between the Virgo galaxies is permeated by hot X-ray emitting gas and, as has become clear recently, by a sparse "intracluster population of stars". So far, stars have been observed to form in the luminous parts of galaxies. The most massive young stars are often visible indirectly by the strong emission from surrounding cocoons of hot gas, which is heated by the intense radiation from the embedded stars. These "HII regions" (pronounced "Eitch-Two" and so named because of their content of ionized hydrogen) may be very bright and they often trace the beautiful spiral arms seen in disk galaxies like our own Milky Way. New observations by the Japanese 8-m Subaru telescope and the ESO Very Large Telescope (VLT) have now shown that massive stars can also form in isolation, far from the luminous parts of galaxies [1]. During a most productive co-operation between astronomers working at these two world-class telescopes, a compact HII region has been discovered at the very boundary between the outer halo of a Virgo cluster galaxy and Virgo intracluster space. This cloud is illuminated and heated by a few hot and massive young stars. The estimated total mass of the stars in the cloud is only a few hundred times that of the Sun. Such an object is rare at the present epoch. However, there may have been more in the past, at which time they were perhaps responsible for the formation of a fraction of the intracluster stellar population in clusters of galaxies. Massive stars in such isolated HII regions will explode as supernovae at the end of their short lives, and enrich the intracluster medium with heavy elements. Observations of two other Virgo cluster galaxies, Messier 86 and Messier 84, indicate the presence of other isolated HII regions, thus suggesting that isolated star formation may occur more generally in galaxies. If so, this process may provide a natural explanation to the current riddle why some young stars are found high up in the halo of our own Milky Way galaxy, far from the star-forming clouds in the main plane.

9 April 2002: Using the ESO Very Large Telescope (VLT) , a team of astronomers from The Netherlands, Germany, France and the USA [1] have discovered the most distant group of galaxies ever seen , about 13.5 billion light-years away. It has taken the light now recorded by the VLT about nine-tenths of the age of the Universe to cover the huge distance. We therefore observe those galaxies as they were at a time when the Universe was only about 10% of its present age. The astronomers conclude that this group of early galaxies will develop into a rich cluster of galaxies, such as those seen in the nearby Universe. The newly discovered structure provides the best opportunity so far for studying when and how galaxies began to form clusters after the initial Big Bang , one of the greatest puzzles in modern cosmology.

26 February 2002: New images of Comet Wirtanen's 1-km 'dirty snowball' nucleus have been obtained with the ESO Very Large Telescope at Paranal (Chile). They show this object at a distance of approx. 435 million km from the Sun, about the same as when the Rosetta spacecraft of the European Space Agency (ESA) arrives in 2011. The new observations indicate that the comet has a very low degree of activity at this point in its orbit - almost no material is seen around the nucleus. This means that there will not be so much dust near the nucleus as to make the planned landing dramatically difficult.