The Cosmic Mirror
By Daniel Fischer
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A German companion - only available here!
Current mission news: MGS (latest pictures!) + Cassini + Stardust

(R)HESSI has completed the on-orbit checkout
while the first X-ray images of the Sun have been released and the new solar observatory satellite (see Update # 234 story 5) has been renamed the Reuven Ramaty High-Energy Solar Spectroscopic Imager: Spectrum Astro, GSFC and Berkeley Press Releases. Calmer space weather ahead: CfA Press Release, CNN. Geomagnetic storms as earthquake-triggers? RP. Aurorae on March 23/24: SpaceWeather.
Update # 236 of Friday, April 19, 2002
Archaeoastronomy sensation from Germany? / Even young quasars shrouded in dust / Big bolide over Germany on famous orbit / Amino acids from interstellar ice / How the Leonids 2001 really worked

An archaeoastronomy sensation from Germany?

It could be the oldest known depiction of the sky, 3600 years old, or a clever forgery - and now it is on display for a short time in a museum: the »Sangerhausen Star Disk« (Sangerhausener Sternenscheibe), a bronze disk that was apparently unearthed during an illegal dig in the German state of Sachsen-Anhalt in 1997 or 1998. The disk, 32 cm in diameter and weighing 2 kg, has been sold twice since on the grey art market, with the price climbing from 16,000 to 165,000 Euros - until the Swiss police could confiscate it this February 23rd from the third group of owners who wanted to sell it for a whopping 380,000 Euros.

Archaeoastronomers had vaguely known about the unusual disk since about 1999, but neither the identities of the original diggers nor the exact location where it was found (together with a few other artifacts) are known. But the apparent astronomical details on its face are intriguing experts nonetheless: There seem to be the Sun (or Full moon), a lunar crescent or eclipse, a »ship« (or the Milky Way) - and at least 29 stars spread randomly across the disk, with the exception of a tight cluster of 7 stars. The latter could represent the Plejades, the Praesepe or the small constellation Dolphin, for example. If genuine, it could well be the first semi-realistic picture of the sky depicted by man.

Until April 28 the disk and the related objects are now on display in Halle, Germany - before the return to the hands of science for restoration and detailled analysis. Metallurgical studies are already indicating that it is old and at least not a simple forgery. All results will eventually be published, probably more than a year from now, and then the disk, if found to be genuine, will be displayed permanently. Perhaps by then we will also have an idea what its original purpose may have been and how it fits into the history of mankind's desire to understand the Universe. (Based the official website and additional information from Prof. W. Schlosser, University of Bochum)

Official homepage of the disk and a Interior Dept. Press Release.
Coverage by RP.

Big planet line-up in the evening sky

taking place in April and May: a special page from the CfA, a growing collection of pictures, the view on April 14 and stories from S&T, CNN, Astron., AP, BBC, Reuters SC ( earlier), RP, NZ, BdW, Sp.
Low Venus could cause UFO reports, German astronomers warn: CENAP News, DPA, RP, RheinZ. It's 5 years after the Hale-Bopp-inspired Heavens Gate mass suicide: NC Times.
Diamond dust halos in Austria: Kaiser's page. How to know it's Easter: ESA Science News. Observing the Moon's Earthshine: Science@NASA.

Even young quasars shrouded in dust, sitting in giant ellipticals, containing big black holes

The understanding of quasars, the most energetic active nuclei of galaxies known, is progressing quickly, some 40 years after the discovery of this astonishing phenomenon. Some of the most recent findings:
  • Even the most distant (and thus youngest) quasars known contain large amounts of cool dust, observations with the James Clerk Maxwell (radio) Telescope in Hawaii have shown. This demonstrates that there was already at least one generation of massive stars that died as supernovae - no other source for the heavy elements in the dust is known. These quasars, with redshifts between 5 and 6 are the most distant known sources of submillimeter radiation.

  • Even distant quasars are hosted by giant elliptical galaxies as are the nearer (and older) ones, observations with the HST have shown which have finally succeeded in imaging the host galaxies of quasars with redshifts around 2. These galaxies are of the same type as those around most z=0.2 quasars. The spectra of the distant host galaxies imply, though, that these elliptical galaxies are still in the process of formation and still actively producing stars (in contrast to present-day ellipticals).

  • Even the earliest quasars contain supermassive black holes of 1 to 10 billion solar masses, Chandra observations of the three most distant cases known (from the Sloan Digital Sky Survey) show, at least indirectly. The three quasars with redshifts of 6.3, 6.0 and 5.9 look similar in X-rays to quasars twice as old to one group of researchers, while another one sees some shift in spectral energy over time.
Dust: RAS Press Release and coverage by BBC, BdW, NZ. Ellipticals: RAS Press Release, Astron. Black Holes: Chandra Press Release and coverage by Sp, RP.

The most distant structure of galaxies known

is a protocluster at z=4.1 - the VLT has detected 20 Lyman-alpha emitters within a projected distance of 1.3 Mpc of the luminous radio galaxy TN J1338-1942: paper by Venemans & al., an ESO Press Release and coverage by Sp and NZ.
Weighing the neutrino with the large-scale structure of the Universe - or rather setting a new hard upper limit: paper by Elgaroy & al., RAS Press Release, NSU. Gravitational lens maps Dark Matter: paper by Gray & al., RAS Press Release, BBC.
Velocity dipole of the Universe measured with distant galaxies! Paper by Blake & Wall. Space-time grainy? NSU. Dimming supernovae w/o cosmic acceleration? PNU, BdW.

Big bolide throws Germany into confusion - bright lights, wrong meteorites and in the end a remarkable trajectory

We are slowly learning more about the Universe from a fireball of about -15th magnitude that streaked over southern Germany on the evening of April 6 (at 20:20:18 UTC) - but we have already learned a lot about the lack of knowledge about things celestial among official institutions, the press and the public at large. While to amateur astronomers it was clear immediately that the light in the sky had been a simple though very bright meteor, great confusion reigned for at least another 24 hours for the remainder of the population: the phenomenon was addressed as either a UFO, a piece of comet Ikeya-Zhang (which was 75 million km away that day!) or reentering space debris.

Even the resolution of the »mystery« was a fiasco by itself: When a women who had witnessed the bolide later found a strange »stone« in her garden, it quickly ended up on the desk of a geology professor who declared it a genuine meteorite from the fireball! So there was the proof that the sky lights were a meteor? No way: A real expert soon studied the specimen and identified it as a piece of bitumen (that had ended up in the garden during road works years ago). Still the hunt for real meteorites from the bolide continues: Since it was captured by 7 of the 25 all-sky cameras, the atmospheric (and heliocentric) trajectory was soon be calculated precisely by Czech astronomers, further restricting the likely strewn field to an area in the Alps in the extreme South of Germany.

They have already learned that the body, before its collision with Earth, orbited the Sun on an elliptic orbit that was quite typical by itself for fireballs which penetrate very deep into the Earth's atmosphere and which can produce meteorites. The aphelion of these orbits lies in the main belt of Asteroids and therefore the asteroidal origin of these bodies is inferred. However, the heliocentric orbit of this fireball has one very significant exceptionality: its orbit is the same as the orbit of the first photographed meteorite fall in the history - the Pribram meteorite fall on April 7, 1959! Both orbits are so close that there is no doubt that both bodies have the same origin. This is considered very important evidence for the existence of asteroidal streams and meteorite streams.

The strange case of asteroid 1950 DA

It is the asteroid with - by far - the highest known probability of an impact on Earth, 1:300, but if it happens, it will be in the 29th century. And there is a pretty simple method to get rid of any possible danger long before calamity strikes. As the original number 1950 DA implies, the asteroid was discovered in 1950, but only recent optical and esp. radar observations have allowed a precise orbit calculation (it's now asteroid number 29,075) - and the discovery of an impact possibility in March 2880. No impacts before that date are possible, and so the strange case is of purely academic nature so far.

1950 DA will come moderately close to Earth again in 2032 and 2074: Then the orbit can be refined much more and the outlook for 2880 will become clearer. If the likelyhood of an impact by that 1-km object goes up a lot, simple remedies are possible: With the help of spacecraft the properties of its surface could be altered so that the Yarkovski effect changes. This effect (that slightly alters a small objects trajectory through the re-emission of solar radiation as heat) is actually responsible for part of the current uncertainty of 1950 DA's future orbit as its actual surface properties haven't been determined yet. (Giorgini & al., Science of April 5, p. 132-6)

The Bolide: a DLR Press Release, a Czech report and a website on the trajectory.
Infrasound data from the event.
Earlier and still earlier AKM and earlier and still earlier CENAP analysis.
News coverage after the "mystery" was no more: AFP, Ananova, NZ (früher), Berliner Zeitung.
Early confused news coverage: Ananova, Reuters, NZ (earlier), Salzburger N., AFP, Vorarlberg Online, Bild, TAZ, Ostseezeitung, Heise, Allgäuer Z., SPIEGEL.

1950 DA: JPL and UA Press Releases and a special page.
Coverage by SD, Dsc, Astron., SC, ABC, New Sci., BBC, CNN, Sp, NZ, RP, BdW, Welt.

The NEO with the highest impact probability

in the next 100 years is 2002 CU11 (although the impact probability, once 1:9000, has shrunk to 1:77,000 on April 9): Sentry entry. Earlier: Tumbling Stone [CCNet (items 3-5)].
UK asteroid centre opens to feed an increased public appetite for knowledge about NEOs: BBC.
Australian science minister ignorant of NEO hazard - in a TV program he expressed his view that the hunt for Near Earth Asteroids is utter nonsense: transcript, more [CCNet], SC, Canberra Times. Why the risk is hard to grasp: SC.

ESA to probe asteroid "blind spot"

between the Sun and Earth - a study has shown that the Gaia spacecraft will be able to see clearly into this 'blind spot' and keep precise track of the Aten population: ESA Science News.

Amino acids form from simulated interstellar ice

New laboratory experiments in the U.S. and Europe have demonstrated that amino acids might form readily in the interstellar medium: In gas mixes based on our knowledge of molecular clouds that condensed on »cold fingers« (standing in for dust particles) and were irradiated by UV light (simulating typical stars) between 3 and 16 different amino acids formed in no time. And since comets are believed to consist of material grown this way, it is more likely than ever now that some of the most important precursors of life have rained with them onto the young Earth. And any other earth forming in the Universe, one may extrapolate: The new lab experiments add to the belief that at least primitive life could be widespread. (Bernstein & al. + Muñoz Caro & al., Nature of March 28, p. 401-6)
MPG, Univ. Bremen, Ames (more) and SETI Institute Press Releases and coverage by New Sci., BBC, SC, Astron., Sp, NZ, RP.

Ethylene glycol found in space

further supporting the view that prebiotic chemistry may first get started in the ISM: NRAO Press Release, NZ.

Some insights and some mysteries surrounding the pair of Leonid storms

in November 2001 have emerged in the ongoing analysis of the tons of visual and video recordings of the rare event (see Update # 230) - and the latest surprising results have been presented once more at the annual meeting of the Arbeitskreis Meteore (Germany's Meteor Working Group) in Kühlungsborn (see the Updates # 222 story 7 and 182 story 3 for the respective stories from 2001 and 2000). Timing-wise the visual and video results agree to within minutes - but the relative heights of the »American« and the »Asian« storm are more controversial than ever.

The latest analysis, presented by R. Arlt and S. Molau, is based on three sources: the worldwide collection of visual observations by several hundred observers (who together recorded over 100,000 Leonids), a pair of two identical intensified video cameras carried to New Mexico and China - and a continuous 12-hour (!) video recording covering both peaks (from dust trails produced by comet Tempel-Tuttle 7 and 4 orbits ago, resp.). The latter was accomplished by the Japanese amateur O. Okamura flying on a regularly scheduled plane from Los Angeles to Taipeh (Taiwan). The visual and esp. the video data need to be treated carefully for systematic effects, and what has emerged after several months of work may still not be the final result:

  • The »American« maximum consisted of two separate peaks 20-25 minutes apart that had about the same height (a Zenithal Hourly Rate of some 1650), although an isolated group of normally reliable observers is reporting a much higher 2nd peak (that the analysts dismiss). The two peaks were at 10:39/43 UTC (derived from the visual and combined video analysis, respectively) and 11:03/02. The visual data also show possible smaller peaks at 9:21 and 12:01 UTC.
  • The »Asian« storm had a sharp peak at 18:16/14 UTC with a ZHR of some 3750, flanked by two lesser peaks at 18:02 and 18:30 UTC - the latter result comes from the visual data and is stable, i.e. independent of the averaging algorithm used. The airborne video data also hint at a pre-maximum at 17:39 UTC that could be related to a third dust trail, 9 revolutions old.
  • The relative strength of the two storms is unclear at this point: While the visual analysis shows the Asian one 2.3 times higher than the American one, the airborne video has a factor of 3 and the pair of groundbased cameras a similar or even larger factor of difference. That discrepancy is probably caused by a strikingly different meteor magnitude distribution in the visual and video records that in itself is unexplained (the videos show far fewer fainter meteors).
Much work thus remains to be done: While most of the reliable visual observers have by now been integrated into the worldwide analysis, there were many more video cameras in action in the U.S., Asia and Australia. A search for local differences (as were seen in 1999, hinting at fine structure in the dust trails) or for periodicities (in 1999 a strong 7-minute period appeared in Western European videos and radar data of the storm) has yet to take place. And there is also the question of where to head for this year's final possible storm(s) under bright moonlight: Some regions in North America, Southwestern Europe and Northern Africa look reasonably promising, according to cloud statistics compiled by H. Lüthen. DF

Yet another amateur comet discovery

has taken place - after Snyder-Murakami we also have a new Utsunomiya to celebrate, and it reached 5th magnitude in April, though close to the Sun: Ephemerides for Snyder-Murakami and Utsunomiya, Snyder's own page and stories from Astron. ( earlier), Sierra Vista Herald, S&T and SC.

Comet discoverer Hyakutake dead

at 51 - he died from a heart aneurysm on April 10: Japan Today, Astron., SC, how he found the comet (another version).

Ikeya-Zhang stars in the morning sky

but the comet, approaching its perigee on April 29, is fading slowly now: An article by Bortle, more info from VSB and J. Jahn, CfA, RAS, JPL and S&T [SR] Press Releases, pictures by Karrer, Jones and Gährken (earlier) and from Finland (scroll down), Spain, Colorado, Stuttgart and Tenerife, coverage by Journal Star (on Ikeya himself) and NSU, SFGate, CNN (earlier), SC, NZ, RP, Sp (on the comet).

Borrelly's nucleus hot and dry

At least the surface of this comet's nucleus did not reveal any water signature to Deep Space One: JPL Release, S&T, BBC.
Comet SOHO-422 close to the Sun - until April 20 you can follow via the Internet the progress of the new-found comet SOHO-422: ESA Science News, NASA News, HotShot, NZ.

ISS Update

Atlantis is on the way back to Earth after delivering the S-Zero Truss to the ISS where the astronauts put it into place during 4 EVAs in mid-April. Before that a Progress had docked to the ISS on March 24, while the next Soyuz, with two visitors, will launch on April 25 and the return of Expedition 4 is delayed somewhat to June: the status, JSC and Boeing Press Releases on the truss, an MSFC Press Release on new SSMEs, ESA Press Releases on taxi passengers in October and April and the 1st ATV, Energia Release on the deployment of Kolibry, Radio Sh. Rel. on Bass and coverage of April 18: AFP, Reuters, BBC, Sp. April 17: AP, AFP, ST (earlier), NZ. April 16: CollectSpace, SN, ST, FT, NZ, Sp. April 15: SN, AFP, Interfax, ST, RP. April 14: SN, ST, Sp. April 13: HC, SN. April 12: NYT, SN, ST, Sp. April 11: BBC, AFP, NZ. April 10: AFP, ST, AN, RP, Sp.
April 9: AFP (earlier and other and yet another story), Sp. April 8: SN, ST (earlier, AP, SC, BBC, NZ (andere Story), AFP (other story), RP. April 7: SN. April 5: AFP, ST. April 4: AN, SN, HC, BBC, ST. April 3: SN (other story), SC, AFP, ST. April 2: NYT, SN, SC. April 1: SC. March 27: AN, ST. March 26: FT, ABC, AFP, SN, SC. March 25: AFP, RP. March 24: ST, SC. March 22: SN, ST. March 21: AP, SR, SC ( other story), ST. March 20: AFP. ST. March 19: HC.
Teacher-in-space program relaunched, with McAuliffe's back-up to fly in 2004, NASA chief O'Keefe has confirmed during a programmatic speech: ST (earlier), AFP, CNN, SN, the full text of the speech. O'Keefe criticized: ST.
NASA classifies shuttle launch times - the exact launch times will not be released until 24 hours before liftoff for the time being; before that only a four-hour window for the launch is available (though often the time can easily be calculated): AP, BBC, ST.

Galileo gets the go-ahead

The European system of navigation satellites will become a reality after the EU transport ministers gave the official go-ahead on March 26: ESA Press Release [SR] (earlier) and coverage by New Sci., BBC, Sp, RP, NZ. Earlier: New Sci., AP, AFP.

The first pictures from the ENVISAT satellite have been released from two of its instruments: ESA Press Release and pics! Coverage by New Sci., BBC, CNN, NZ. Trouble with a Terra instrument resolved: SC ( earlier).

Shenzhou 3 launched, capsule returns

China has launched the third Shenzhou spacecraft on March 25, and the descent capsule made a safe landing on April 1 - the successful flight could pave the way for the first launch of a manned spacecraft as early as next year: Coverage of April 15: SC. April 11: Economist, April 9: SD. April 4: SC. April 3: CNN. April 2: SD, Peop., AFP, New Sci., NZ. April 1: Xinhua, AFP, AP, SN, CNN, BBC, ST, SD. March 31: SD. March 28: Peop., SD, ST. March 27: New Sci., AFP. The launch: CCTV pics, SD (analysis), Jane's, Peop. Daily, BBC, New Sci., CNN, AP, SC, ST, NZ, Sp.

Daily THEMIS images of Mars

are now being put online in a pretty raw format: ASU Press Release [SN], FT, all pictures and the first release. Odyssey one year in space. And the MGS is also delivering pictures all the time.

Beagle 2 cleared by ESA after the status was rather perilous just a few months ago: SD.

Why Martian water is found on the north pole, not the south: Caltech Press Release, NSU, BBC, SC, AFP. How it hides under the SPC: Newcastle PR. Chlorophyll-on-Mars speculations: Astrobiology abstract, BBC, SC, ST, Sp.

Voyager 1 'serviced' over 12.5 billion km distance

Flight controllers activated a backup position-sensing system, including a Sun sensor and star tracker, on the spacecraft launched 25 years ago: JPL Release, BBC, CNN, DDP.

Cassini adjusts trajectory - the spacecraft successfully completed a course adjustment April 3 during its journey toward Saturn: Status Report.

Bad outlook for a 2006 Pluto mission

Top NASA officials said on April 12 it was highly unlikely that a mission to Pluto would be launched by 2006 - and a mission to Jupiter's watery moon Europa also has been canceled: LAT. The scientists continue the preparations for New Horizons anyway: SwRI Press Release.

Mercury orbiter mission passes major milestone - MESSENGER project cleared to build spacecraft: JHU APL Press Release, AN, ST. Dreams of a European "Venus Express": proposal, RAS Press Release, BBC, SC.

NASA Explorer candidates downselected

Following detailed mission concept studies, NASA intends to select two of four mission proposals for the next missions in the Explorer Program by early 2003 - the two MIDEX missions will be launched in 2007 and 2008: JPL Release.

Hubble resumes scientific work after servicing

After three weeks of in-orbit checkout, following its deployment from Space Shuttle Columbia on March 9, the Hubble Space Telescope has been declared healthy and fit: GSFC Release [SN], SC. After Hubble, the NGST: FT.

SIRTF satellite delivered for testing, astronomers anticipate clues to galactic mystery going back to origin of time: Cornell PR.

TDRS spacecraft stranded in transfer orbit

A recently launched NASA communications satellite is stranded in a useless transfer orbit as engineers work on a problem with the propulsion system of TDRS-I: Boeing statement, Homepage, BBC, KnR, OS, ST, FT, SR, SC, UPI, NZ.

First Atlas V prepares for July launch with a "Wet Dress Rehearsal": SN. Booster test may have shown problem: SC. Atlas V & Delta IV: SC.

Old Pegasus reenters with two dead satellites

In 1996 neither HETE nor SAC-B could separate from the rocket stage (see Update # 12), now all three objects have (mostly) burned up over China: GSFC info, SC ( earlier). Rocket fragment lands in Uganda: AllAfrica.

Progress for the commercial solar sail satellite project: Team Encounter Press Release.

Two 'neutron' stars actually consisting of quark matter?

So far the evidence is pretty indirect, but extremely compact stars made of matter never seen outside high-energy lab experiments could explain puzzling X-ray data: papers by Drake & al. and Yakovlev & al., a Chandra Press Release and coverage by NSU, New Sci., NYT, BBC, SC, AFP, SC, ST, APOD, Welt, DDP, RP.

One candidate may be a neutron star after all, as it is more distant than believed, according to the latest HST astrometry: paper by Walter & Lattimer.

And the other one is actually the youngest radio pulsar, born 820 years ago - the GBT has detected the faint pulses: paper by Camilo & al., NRAO Release, BdW.

Tons of Planetary Nebulae

have been found in the Milky Way - the number of aged stars in their death throes revealed is rapidly overtaking the entire population discovered during the last 75 years: RAS Press Release, SC.

Formation of helium stars explained? A class of variable stars named after their prototype R Coronae Borealis (RCrB) and a related group called 'extreme helium stars' could be the products of mergers between pairs of white dwarf stars: RAS Press Release, Astron.

Chandra observations of merging galaxies

reveal a very diffuse, extended X-ray emission that seems to arise from very hot (a few million K) material ejected from the galaxies: RAS Press Release. Galaxy collision visualization created for big planetarium projection: STScI, NASM Releases. Chandra views the Coma cluster: MSFC Release.

Disturbed spiral galaxy ablaze with the light from millions of new stars, HST images of NGC 7673 show: ESA Science News, Astron., CNN. Interstellar searchlights catch star factories in their beams: RAS Press Release.

New kind of star cluster discovered in nearby galaxies

Much larger and fainter than typical globular clusters, the new objects were first detected in Hubble Space Telescope images of the lenticular galaxy NGC 1023: UCSC Press Release (more), Sp, NZ.

Gemini captures multi-dimensional movie of active galaxy's core with spectroscopy of the gas movements in NGC 1068: Gemini Press Release, NSU, Sp.

Star formation stages simulated in the lab

In a laboratory in Nottingham, scientists are now creating the uniquely harsh conditions encountered in interstellar space: RAS Press Release, BBC, SC.

Young stars like to hang around in crowds and undergo chaotic close encounters with each other during their formative years, one of the largest and most complex computer simulations has shown: RAS Press Release.

Hunting for 'Vulcanoids' from a fighter plane

Only from above most of the atmosphere astronomers might have a chance to glimpse asteroids that could exist very close to the Sun: DFRF Press Release [SD], AN.

What we learned from NEAR when it touched down on Eros: Science@NASA. Preparations for MUSES-C: SC. An impact that caused an earthquake? "Rock solid evidence" in the case of Manicouagan: GSA Press Rel.

There are more asteroids in the main belt

than believed until now, an analysis of data from the long-defunct ISO satellite implies: ESA News [ESA Science News], NSU, Astron., SC, BdW, NZ.

Speculation about a 5th terrestrial planet responsible for the Heavy Bombardement early in the Solar System's history: SC, WELT.


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Compiled and written by Daniel Fischer
(send me a mail to dfischer@astro.uni-bonn.de!), Skyweek