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29 Ottobre 1991: This is a ground-based photo of the first minor planet ever to be visited by a spacecraft. On October 29, 1991, the NASA spacecraft Galileo will pass minor planet no. 951 Gaspra on its way to Jupiter where it will arrive in December 1995. The distance from Gaspra to the Earth will be 410 million km at the time of the fly-by.

22 Ottobre 1991: Observations with telescopes at the La Silla observatory have revealed that the image of an extremely distant quasar, known as Q1208+1011, actually consists of two images very close to each other. It is the most distant and also the brightest quasar ever observed to have a double image.

24 Settembre 1991: ESO is now awarding a major contract for its Very Large Telescope (VLT) to the "AES Consortium" of three Italian companies. It concerns the construction of the main mechanical structures of the four 8-m VLT unit telescopes, each of which will weigh more than 440 tons and yet must be machined with sub-micron precision in order to allow astronomical observations of the highest quality.

24 Settembre 1991: Observations with the 3.5-m ESO New Technology Telescope by a European group of astronomers have shown that a very compact object in an extraordinary binary star, known under the astronomical designation 88433, is most probably a neutron star and not a black hole, as previously believed by most scientists. Improved observation techniques have allowed a reliable determination of the mass of this object: it is now found to weigh less than the Sun and is therefore not massive enough to be a black hole.

16 Luglio 1991: The lonely Atacama desert is a perfect place to study distant celestial bodies in the space around us. The following story shows how this may be done, not only through powerful astronomical telescopes at isolated mountain-top observatories [1], but also down on the barren desert plain in a much more direct way.

31 Maggio 1991: The ESO New Technology Telescope on La Silla has again proven its extraordinary abilities. Known since two years as the world's best optical telescope [1], it has now produced the "deepest" view into the distant regions of the Universe ever obtained with any ground-or space-based telescope. The new picture shows enormous numbers of extremely faint and remote galaxies whose images almost completely fill the field of view. Expressed in astronomical terms, the picture reaches beyond magnitude 29 [2].

26 Aprile 1991: The decision to place the world's largest telescope, the ESO 16 metre equivalent Very Large Telescope (VLT) on the Paranal mountain in the Chilean Atacama desert [1], taken by the ESO Council on 4 December 1990, was today followed up by an important next step. During a small ceremony at the European Southern Observatory Headquarters in Garching, two major contracts were signed which will together define the future shape of the VLT Observatory and its infrastructure.

22 Febbraio 1991: It was early in the morning of Tuesday, February 12, and ESO astronomers Olivier Hainaut and Alain Smette [1] did not know what to believe. Observing with the Danish 1.54-metre telescope at the La Silla observatory, they had just finished a one-hour exposure of a small sky field in the constellation of Hydra (the Water Snake). This work was part of the ESO monitoring programme of famous Comet Halley and the astronomers felt that something was quite wrong.

06 Febbraio 1991: A test run for the manufacture of mirror blanks in the 8-metre class, for use in the world's largest optical telescope, the ESO 16-m equivalent Very Large Telescope (VLT), has been successfully performed at Schott in Mainz, Germany [1]. The test blank had a diameter of 8.6 metres and a surface area of more than 55 metres squared. This is the first time that has been possible to cast such a large glass-ceramic blank in one piece. To accomplish this impressive feat, Schott has developed a number of new technological procedures.

17 Gennaio 1991: Acting on information received from Danish scientists working with an X-ray telescope on a Soviet satellite, astronomers at the ESO La SiIla observatory in Chile have discovered a strange new star in the southern constellation of Musca (the Fly). Preliminary observations with the ESO 3.5-m New Technology Telescope indicate that the object is a nova, most probably a small, very dense star in a binary system whose brightness in a dramatic event has suddenly increased about 1000 times. The available optical and X-ray observations point to a quite unusual object.

04 Dicembre 1990: The Council of the European Southern Observatory, in session today at the ESO Headquarters in Garching near Munich, unanimously decided that the world's largest optical telescope, the 16-metre equivalent Very Large Telescope, shall be placed on Cerro Paranal [1], an isolated mountain top at 2664 m altitude in the central part of Chile's Atacama desert, some 130 kilometres south of the town of Antofagasta and 12 kilometres from the Pacific coast.

09 Novembre 1990: A very large, white spot has recently appeared on the giant planet Saturn [1]. It is probably a great storm in the planet's atmosphere, which has been initiated by upwelling of clouds from the lower layers into the uppermost regions. The spot began as a small, white feature in Saturn's northern hemisphere and has since developed rapidly so that it now appears to completely encircle the planet's equatorial regions. "Great White Spots" have been seen on Saturn in 1876, 1903, 1933 and 1960 (see below), but the present one seems to be the biggest of them all.

31 Ottobre 1990: Observing with the ESO New Technology Telescope, three European astronomers have discovered two previously unknown celestial objects which are seen in the direction of the mysterious centre of our galaxy, the Milky Way. One of the new objects has a comparatively blue colour and appears to be the actual Galactic Centre, at a distance of about 28 000 light-years. It has required a telescope with the penetrating power of the NTT to see through the dense, interstellar dust clouds (which effectively hide the central area from our view) in order to obtain the first optical image of the Galactic Centre.

24 Ottobre 1990: Astronomers working at the ESO La Silla observatory have just discovered the most distant "normal" galaxy known so far. It has been given the designation G 0102 - 190 and its distance is so great that the light we observe from it was emitted when the Universe was only one third as old as now [1].

29 Settembre 1990: By decree of the International Astronomical Union, a newly discovered minor planet (asteroid) in the solar system has been given the name Portugal, honouring this European country.

27 Settembre 1990: A long-term astronomical study of spiral galaxies, initiated almost a decade ago at the European Southern Observatory, has recently produced intriguing results about the presence of cold matter in the Universe. They have a direct bearing on the so-called "missing mass" problem, one of the major unsolved riddles in astronomy.

25 Settembre 1990: These impressive photos of Comet Levy (1990c), one of the brightest comets in recent years, were obtained with the ESO 1-metre Schmidt telescope at the ESO La Silla Observatory, on September 12 and 14, 1990. On these dates, the comet was 104 and 111 million kilometres from the Earth and 179 and 176 million kilometres from the Sun, respectively. It will reach its perihelion (the point in the orbit which is closest to the Sun) on October 24.

26 Luglio 1990: Famous Comet Halley, now receding from the Sun after its perihelion passage in early 1986, has recently entered into a state of hibernation which will last until shortly before the next passage in 2062.

13 Giugno 1990: Most of the dust that is ejected from a comet's nucleus (i.e. the "dirty snowball" at its centre) assembles in a thin “sheet'' near the orbital plane in which the comet moves around the sun. This sheet is very thin and is difficult to observe unless it is viewed directly from the side. On June 6, 1990, the Earth crossed the orbital plane of Comet Austin, allowing such a unique, side-on view.

23 Maggio 1990: With the help of "adaptive optics," a revolutionary optical concept (eso8908), infrared astronomical images have been obtained with the ESO 3.6 m telescope at the La Silla observatory which are as sharp as they would be if the telescope were situated in space. This is the first time in astronomy that a ground-based telescope of this size has been able to directly register during long time periods stellar images with a sharpness that corresponds to the theoretically possible limit.