European Southern Observatory
For many years astronomical images from the world's telescopes were reserved for an elite of astronomers and technical people. Now anyone with a desktop computer running Adobe Photoshop software can try their hand at crafting astronomical images as beautiful as those from the Hubble Space Telescope. A free software plug-in, released today, makes a treasure trove of archival astronomical images and spectra from the NASA/ESA Hubble Space Telescope, the European Southern Observatory's Very Large Telescope, the European Space Agency's XMM-Newton X-ray observatory, NASA's Spitzer Space Telescope and many other famous telescopes accessible to home astronomy enthusiasts.
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.
Active galaxies are breathtaking objects. Their compact nuclei are so luminous that they can outshine the entire galaxy; ''quasars'' constitute extreme cases of this phenomenon, their powerful engine making them visible over a very large fraction of the observable Universe. It is now widely accepted that the ultimate power station of these activities originates in supermassive black holes with masses up to thousands of millions times the mass of our Sun. For comparison, the one in the Milky Way galaxy has only about 3 million solar masses. The central black hole is believed to be fed from a tightly wound accretion disc of gas and dust encircling it, in a donuts-shaped torus. Material that falls towards these gigantic ''vacuum cleaners'' will be compressed and heated up to enormous temperatures. This hot gas radiates an incredible amount of light, causing the active galaxy nucleus to shine so brightly.
During the coming evenings, everybody under clear skies will be able to enjoy a beautiful view in the twilight. Right after sunset, planet Venus is visible as a brilliant point of light above the western horizon - and two other planets, Mars and Saturn, are seen to the left of Venus as somewhat less bright objects. More to the south and higher in the sky, planet Jupiter is also prominent.
In the evenings of April 22 and 23, the thin crescent of the Moon will be located near Venus and Mars, further adding to the splendor of this sight (the drawing shows the configuration in the evening of Friday, April 23).
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 during recent commissioning observations with the "Simultaneous Differential Imager (SDI)", a novel optical device, just installed at the NACO Adaptive Optics instrument.
By measuring polarized light from an unusual exploding star, an international team of astrophysicists and astronomers has worked out the first detailed picture of a Type Ia supernova and the distinctive star system in which it exploded. Using the European Southern Observatory's Very Large Telescope in Chile, the researchers determined that supernova 2002ic exploded inside a flat, dense, clumpy disk of dust and gas, previously blown away from a companion star. Their work suggests that this and some other precursors of Type Ia supernovae resemble the objects known as protoplanetary nebulae, well known in our own Milky Way galaxy.
On May 7, 2003, Mercury, the innermost planet in the solar system, will pass in front of the Sun and produce a solar eclipse. But this event will hardly be noticed. Mercury's small disk will indeed barely be bigger than the point of a pencil. Even the smallest sunspots on the solar surface are as big as the Earth and measure 10,000 km or more in diameter, while Mercury's equatorial diameter is only 4878 km.
