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is now available, including many photographs! And there are many more reports from the eclipse (see also last issue): |
Update # 144 of August 23rd, 1999, at 12:45 UTC (some links added Aug. 28th)
Cassini's Earth Fly-by executed in perfectionThe Saturn-bound Cassini mission successfully completed a highly accurate pass of Earth at 03:28 Universal Time August 18. The flyby gave Cassini a 5.5-kilometer-per- second boost in speed, sending the spacecraft on toward the ringed planet more than 1 billion kilometers away. Engineers at NASA's Jet Propulsion Laboratory confirmed that the spacecraft flew past Earth at an altitude of about 1171 kilometers, passing most closely above the eastern South Pacific at -23.5 degrees latitude and 231.5 degrees longitude. Cassini may have been visible from small islands in that area, such as Pitcairn Island or Easter Island. The spacecraft remains in excellent health as it continues along its seven-year-long journey to Saturn. |
JPL Press Release, NASA Science News and ESA Science News. Coverage by ABC, BBC, CNN, MSNBC, Space.com and SpaceViews. Scientific American on the Cassini controversy. Early reports on science done during the Earth fly-by from ESA. Cassini imaged from Earth - by an amateur: Garrad's views. |
Another idea why the corona is so hotcomes from observations by the TRACE satellite - and the discovery was made by an unrelated researcher making use of the open data policy of this satellite (a general NASA trend these days). Coronal loops, immense coils of hot gas on the surface of the Sun, vibrate wildly after the blast wave from a solar flare hits them. However, their dance is quickly squelched by resistance from the Sun's corona: It restricts motion due to internal friction hundreds of millions of times greater than expected, according to the TRACE observations. This friction or viscosity may help explain why the corona is more than 100 times hotter than the Sun's surface. The discovery would not have been possible without the high resolution of the TRACE spacecraft. |
GSFC Press Release. Meanwhile other ideas about coronal heating were tested by several experiments during the recent solar eclipse that took place in Romania and Bulgaria. While the SECIS and Williams College teams imaged the corona with high speed, a group led by E. Kononovich tried to measure velocity fields in the corona with Fabry-Perot interferometry. Stay tuned... And have you seen the other scientific images of the Sun from August 11th, delivered by SOHO and many other instruments? For some of the European sites the sun was partially eclipsed... |
The story of galaxy evolution in full colorStrong evidence that galaxies grow when smaller clumps of stars and gas merge has been found by looking at the galaxies in the Hubble Deep Field in detail - and there is also evidence that the bar structures seen at the centres of some spiral galaxies formed relatively recently. A popular theory claims that most elliptical galaxies formed from the collision of two spiral galaxies. In this scenario, the spiral arms are destroyed and the gaseous material is expelled or converted into stars. The HDF - analyzed with new techniques - contains striking evidence that distant ellipticals are varied in their internal colour properties, supporting the idea that merging has indeed taken place.The study has also addressed the history of spiral galaxies, such as our own Milky Way. A long-standing puzzle is why some of these systems have bar-like features in their centres. By counting the fraction of barred and non-barred galaxies existing at different eras in the past, the first evidence was found that bars may be a relatively recent phenomenon. Few bars are found in the most distant spirals seen more than 5 billion years ago. This may be because bars develop as unstable features only when a spiral has grown to a certain size. |
R.A.S. Press Release. Pictures and papers relating to this story. A related story: Observations of the growth of a galaxy cluster were the first guest observations with the VLT - ESO Press Release. And another one: Understanding 10 billion years of cosmic evolution on a supercomputer: R.A.S. Press Release. Book reviews: Die Zeit on German books on the big questions of cosmology. |
Molecular hydrogen major constituent of Dark Matter?Before one speculates on exotic particles, the census of 'ordinary matter' inside galaxies should be completed, the controversial ISO detection of lots of molecular hydrogen in a galaxy implies: an early conference abstract and recent ESA Science News - there is no published paper yet.Faintest Methane Brown Dwarf discoveredat ESO: The mass of NTTDF J1205-0744 is probably about 20-50 times that of Jupiter, and its temperature is around 1000 K, suggesting an age of 500 to 1000 million years - paper, ESO Press Release.Planet found orbiting two stars? That's what microlensing data suggest: a preprint; BBC, SpaceViews stories. Neptune's rings remain mysterious - there still isn't a complete theory for them: Nature papers by Sicardy & al., Dumas & al. and a review; reports by Space.com and Explore Zone. BTW: It's now 10 years after Voyager 2 was there! Matter's Final Plunge on Black Hole Roller Coaster Detected?The detection of a red-shifted absorption feature in the emission spectrum of the core of the galaxy NGC 3516, seen by the ASCA X-ray satellite, is cited as evidence for a Black Hole in action: the paper, a GSFC Press Release, ABC, BBC, MSNBC stories.Next Millenium Program satellites only cake-sizedNASA plans to cook up three cake-sized satellites packed with tiny technologies for a mission set to launch in 2003: a NASA Release and Space Daily, Space.com, SpaceViews and CNN coverage.Hybrid rocket motor undergoes first significant firingA rocket motor that could push payloads into space more safely, cleanly and cheaply than conventional solid and liquid fuels passed muster during its first significant firing: a NASA Release and Space Daily and CNN coverage. This is one of several new frontiers in rocket science in the news recently, such as the "Breakthrough Propulsion" discussed by Space Daily. |
Strikingly detailled radar images of asteroid 1999 JM8have been obtained in early August with the Arecibo observatory: Cornell and JPL Press Releases, Photojournal pictures, an earlier Arecibo report, the JPL asteroid radar pages, an early JPL report, ExploreZone and Space.com coverage.Now 1 million involved in SETI@homeThe project has surpassed the magical mark - and still no alien has phoned in: BBC story.
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The U.S. site of this Cosmic Mirror has been visited
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Compiled and written by Daniel Fischer
(send me a mail to [email protected]!), Skyweek
