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Phobos Volume 33 Number 7 Contents 1) Meetings. 2) Society News. 3) Guest Speaker. 4) Sky Diary. 7) Autumn Variables.. 9) Keeping Abreast. 16) Solar Eclipse. Ken Willoughby Ken Willoughby. Professor David W. Allen. Derek Hufton. Melvyn Taylor. Clive Down. Melvyn Taylor. October 2006 Meetings October Meetings 3rd. Members Night. 5th. (Thurs.) Committee meeting. 10th. 'The Chemistry of Interstellar Dust.' Professor David W. Allen. 16th. (Mon.) Visit: 7:00pm-9:00pm. Castleford Ranger Guides. 17th. The Open University SXR208 Astronomy Course. Kevin read. 24th. The November Sky. Ken Willoughby. 31st. Open Night. 7:30pm-10:00pm. 1 SOCIETY NEWS. KEN WILLOUGHBY. September has been an eventful month with speakers. Firstly Sir Arnold Wolfendale came and talked about 'The Search for Intelligent Life' and secondly Professor Mark Bailey from Armagh (both at short notice.) Arnold suggested we contacted Patrick with a view to holding an annual 'Patrick Moore Lecture' where we would invite top speakers from all over the World. Patrick was 'over the Moon' at this and the first of these was on September 26th by Mark Bailey entitled 'New Results and Problems of Cometary Origin.' People are already being contacted for next year so watch this space.. LEEDS ASTROMEET 2006. Date: Saturday, 11th November 2006, Doors open 9.00 am. First speaker 10.00 am. Last speaker 5.10 pm. Tickets on door: £10.00 Venue: The Clothworkers Centenary Concert Hall and Foyer, School of Music, Leeds University (a 300 seat auditorium) (see venue at http://webprod2.leeds.ac.uk/campusmap/detail.asp?ID=13) (or a map at http://www.universallyleeds.co.uk//maps/campusmap.pdf) Speakers: Tom Boles (BAA) "Type I Supernovae - the new stars of Cosmology" Professor John Brown (Astronomer Royal for Scotland) "The Uncertain Universe - Magic of the Cosmos" Dr Allan Chapman (Oxford University) "Mary Somerville and the Lady Astronomer" Dr Simon Green (Open University) "Stardust - a new view of Comets" Nik Szymanek (BAA) "Photographing the Night Sky" Trade stalls already confirmed include: Earth and Sky Books, Aurora Books, Chris Marriott's Skymap, Cape Instruments Green Witch Telescopes, Opticstar Ltd, British Astronomical Association Stockport Binocular and Telescope Centre, Astronomica Further details can be found on the the Leeds Astronomical Society website: http://www.leedsastronomy.org.uk 2 TUESDAY OCTOBER 12TH. 'WE LIVE IN A DUSTY.UNIVERSE!' PROFESSOR DAVID W. ALLEN. Following a PhD degree at Keele, and a research fellowship at Cambridge, David came to live in Dronfield in 1969, when he started work as a lecturer in Chemistry at the then Sheffield College of Technology, which shortly afterwards became Sheffield Polytechnic, one of the first of the new ‘Polytechnic’ institutions and which eventually became Sheffield Hallam University in the early 90’s. He retired as Professor and Head of Chemistry in 2002, but is still active in the University as an Emeritus Professor, helping out with the work of a research group and writing and editing books and other publications. He now has the time to pursue interests in chemical aspects of astronomy and a bit of scientific journalism. 3 Sky Diary: October 2006. Derek Hufton. Monthly Highlights: October is a very quiet month for planet watchers. Jupiter is quite low in the west-southwest at dusk, and Mercury puts in an appearance there even lower, requiring binoculars to find. The only planet easily visible is Saturn, which is high in the southeast before dawn. The reliable Orionids meteor shower peaks this month and is favourably placed due to a New Moon at maximum activity. Dates & Time: Sunday 1st October is the 274th day of the year and it is also number 2454009 in the Julian Calendar. The Sun: Rotation number 2049 of Carrington’s series begin on October 18.55 respectively. During the month the Sun’s axis of rotation is tilted to the east of the vertical some 26.0o at the start of the month and by month end it will be 24.5o to the east. The Sun’s disk is also tilted away from us by 6.4o at the start of the month ending the month tilting away from us by 4.4o – crucial data for you sunspot plotters! The Moon: In the Farmers Almanac, the October Full Moon is called the Hunter’s Moon. In other places it is also referred to as the Blood Moon. However, as the definition of the Harvest Moon is the full Moon closest to the September Equinox, the title this year goes to the October Full Moon, occurring 14 days after the equinox – confusing or what? The waning crescent Moon appears a few degrees to the upper left of Saturn at dawn on the 16th. Back in the evening sky, on the 24th the thin waxing crescent lies very low in the southwest, well to the left of Mercury and Jupiter. The next night it is a little higher and farther left of the two planets – but only 4o left of 1stmagnitude Antares. The Moon's Phases are: New Full 22d 05h 14m 07d 03h 13m 1st Qtr 29d 21h 25m Last Qtr 14d 00h 26m The Moon is at Perigee (closest approach to the Earth) on October 6th at 14h when its apparent diameter will be 33’ 26”. Apogee (furthest approach) occurs on October 19th at 10h with apparent diameter of 29' 26". The maximum Libration points of the Moon’s ‘wobble’ occur on October 12th and 27th, the main extra tilt being visible at Position Angles 229o and 42o respectively. This means that you get a chance to ‘peep round the edge’ of the lunar limb even more on these dates. Remember that Position Angle is measured from North through East on the face of the Moon (North=0 o, East=90o, South=180o, West=270o) and it tells you where to concentrate your telescope. Mercury: Reaches its greatest elongation of 25o from the Sun on the 16th, shining at magnitude –0.1. This elongation will be happening very low in the sky at twilight. On the 17th, about 30 minutes after sunset, you’ll find Mercury just 4o below Jupiter. The two planets are in conjunction in Right Ascension on the 25th and 28th, with Mercury lower left of Jupiter on both dates. Their very low altitude will make them difficult to spot.. 4 Venus: Is in conjunction with the Sun on the 27th. Early in the month you might still catch Venus barely above the eastern horizon before sunrise; then it’s gone. Mars: Is in conjunction with the Sun on the 23rd and is therefore not visible this month. Jupiter: Is still easily visible as the month commences, shining at magnitude –1.8. It is located low in the west-southwest in early twilight. By the end of the month it will be so low that you’ll probably need binoculars to locate it. Saturn: Rises in the northeast at around 3am, shining at magnitude +0.5, at the start of the month. By the end of the month the planet rises just after midnight. The best time for observing will be just before dawn, when Saturn is high in the sky and is much more likely to show a steady and sharp image. The rings are now tilted by only 13o. Uranus and Neptune: Are both well up by mid-evening, in the southeast and south respectively. Uranus will be shining at magnitude +5.8 with Neptune somewhat dimmer at +7.9. Check out the Sky & Telescope website (http://skytonight.com/observing/objects/planets/3311356.html) or the BAA Handbook for finder charts. Meteor Showers: The major shower active this month are the Piscids, Orionids and Taurids. The Piscids is another multiple-radiant ecliptic complex with low rates. The Orionids, associated with Comet Halley, usually has fast meteors with a high proportion of persistent trains. The shower has a flat maximum with several sub peaks and is favourable this year. By contrast the Taurids has slow meteors, often bright, but not the rich fireball source suggested in some books. It starts activity this month, although doesn’t peak until early November. Full details as follows: Shower Limits Maximum RADIANT ZHR RA Dec Piscids Sep-Oct Oct 13 ? 01h 44m +14o 21 days Orionids Oct 16-27 Oct 20 25 06h 24m +15o 28 days Taurids Oct 20-Nov 30 Nov 3 10 03h 44m 03h 44m +14o +22o 13 days 5 Moon at Maxm. 6 Looking South from the observatory @ 22:00h on October 15th. 7 A Selection of Autumnal Variables. Melvyn Taylor. Stars from magnitude 2 to 10. Eta Aquilae: Discovered by Edward Pigott (York) in 1874 this easily found Cepheid variable lies under Altair and changes from mag. 3.5 to 4.4 every 7.17days. Comparison stars beta Aql mag. 3.21 and iota Aql at mag. 4.36 are very useful. This young, large star changes its temperature and surface area with regularity. RZ Cassiopeiae: An eclipsing binary in a binocular field of iota Cas varying from mag. 6.2 to 7.7 in the orbital period of the system, 1.195 days. The total duration of an eclipse is 4.8h. The star is predicted to be faint at one of its primary minima on Oct 02d at 20.8h (UT). Over long intervals the period of the system changes by about 15 minutes. Mira (omicron Ceti): This infamous variable probably first recorded to be changing by Fabricius in 1596 lies 420 light years away. During October the star is nearing a minimum about mag. 9 to 10. Its extreme mag. range is 2.0 to 10.1 in a period of 329 days. This is a huge star having its disc imaged at 0.048 arc seconds, corresponding to a diameter of around 6 astronomical units (450 million kilometres). Not far from delta Ceti. AF Cygni: The star is a typical semi-regular giant star which has been catalogued varying from mag. 6.4 to 8.4 with a mean period of 94d. Interest in these type stars is that the period is often poorly expressed and it may vary slowly, become irregular or may show at a constant brightness. It is probably best found by its location near delta Cyg. RY Draconis: A typical semi-regular variable star that is circumpolar and relatively easy to find being in a triangle of bright stars labelled 7 , 8 and 9 Draconis. The overall changes are from mag. 6 to 8 with a dubious period of 172 days. All that is required is a small binocular and clear skies! AG Draconis: A star in outburst at present and around magnitude 8.5 or thereabouts; at its quiet times visual mag. 10.0. It is an unusual eruptive binary object (known as a symbiotic) with a recent active phase when it was in outburst for 5 years from 1981. Being circumpolar from the UK at declination 67* the star is in a relatively bland area between the brighter stars of the Little Bear and the curving Dragon. UW Herculis: Easily found near pi and rho Her (the left/east shoulder of the Giant) using a binocular this semi-regular variable has recently livened and is showing its period of about 100d with a brightness factor change of about 2.3 (mag. 7.8 - 8.7). alpha Herculis (Rasalgethi): One of the largest stars known but W.Herschel did not know that when he discovered its variability in 1795. It is a semi-regular, reddish, looking naked-eye star that shows slow brightness changes. There are 3 stars that show the combined light some 380 light years away. It is about mag. 3.3 at present. 8 Sheliak (beta Lyrae): One of the most observed and researched stars in the sky. John Goodricke discovered the changes from York (1784) and his explanation was that one star was being eclipsed by another in co-orbit. With the naked-eye the changes are from mag. 3.3 to 4.3, the star having deeper fades every 12.94d. In between there is a lesser dip to mag. 3.8. Sheliak has a luminosity 2600 times that of our Sun, it is 900 light years away. Gamma Lyr is mag.3.23 and kappa Lyr 4.34 convenient comparisons. X Ophiuchi: Dscovered by the Rev'd T. Espin in 1886 this long period variable (6.6 to 8.8, period 329d) is similar in nature to Mira and frankly not easy to find. But once found its location is easily remembered since it is adjacent a small triangle of bright stars with a mag. 5.4 star to its west in the same small field of view. GO Pegasi: A few degrees from alpha Pegasi (Markab) this "red" looking star changes from about mag. 7 to 8. The star is in a class of evolved giant stars with no charted periodicity in its light variations. Algol (beta Persei): Ane of the most famous stars stars in the sky with an intriguing name. The name has been translated as the Demon Star associated with the eye of the Gorgon, Medusa, within the mythology tales of the hero Perseus. It is likely that Montanari first recorded the star's variability in 1667 yet John Goodricke in 1782 investigated a continuous series of its changes and came to the explanation of these as an eclipse in a system of stars. This is the first eclipsing binary star recorded and it provides a long base-line for understanding period changes and how stars in close proximity interact. The distance between the main stars is only 0.07 astronomical units (26 times Earth to Moon). The star is predicted to be faint at a primary minimum on Oct 19 at 22.4h and at other intervals of its period 2.867d. It changes from mag. 2.1 to 3.4. A host of bright comparison stars are nearby but rho Persei, the nearest is also a variable so it is wise not to use this. HU Tauri: A star in a similar mould to Algol an eclipsing binary not far from Aldebaran (alpha Tauri). Using a binocular the object varies mag. 5.5 to 6.9 every 2.05 days with the eclipse lasting at total of 7.7 hours. V Ursae Minoris: This is not that easy to find since care is needed as the object is one of 4 in a near line that may be easily confused. In the last few years this semi-regular has moved out of a long irregular phase and is now showing strong variations from 7.2 to 8.8 in a period of about 72 days. Observations by the writer using small binoculars of some of these objects are summarised in the light curves. Most of these variable stars are to found by reference either to planetarium software or star charts, for example, Atlas of the Night Sky, 2005, Collins. Charts giving comparison stars and magnitudes may be obtained in paper from the writer or by reference to the BAA variable star section web pages: http://www.britastro.org/vss [Data: General Catalogue of Variable Stars; location charts: AAVSO] MDT 2006 August. 9 KEEPING ABREAST. CLIVE DOWN. HUBBLE FINDS PLANET'S STELLAR COMPANION STSI The Hubble space telescope has for the first time identified the parent star of a distant planet discovered through gravitational microlensing. Microlensing occurs when the gravitational field of a foreground star amplifies the light of a background star that momentarily aligns with it. The particular character of the light magnification can reveal clues to the nature of the foreground star and any associated planets. However, without identification and characterization of the foreground star, little can be said about the accompanying planet. The newly discovered host star, catalogued as OGLE-2003-BLG-235L/ MOA-2003-BLG53L, has a planetary companion that was discovered in 2003 through ground-based gravitational micro-lensing. A planetary companion of a foreground star can produce additional brightening of the background star. The additional brightening can reveal the planet, which is otherwise too faint to be seen by telescopes. The Hubble images allowed the research team to resolve the background source star from its neighbours in the very crowded star field in the direction of the centre of our Galaxy. The star appeared to be about 20% brighter than expected; the additional brightness is most likely from the foreground lens star, which hosts the planet. Hubble could not resolve the two stars, but, by taking multiple images through differently-coloured filters, it recorded a colour offset in the overlapping images of the two stars. That is possible because the foreground star is redder than the background star. From its colour, the researchers were able to make a crude estimate of the type of the star, and thereby obtain its distance as 19,000 light-years and the planet's mass as 2.6 Jupiter masses. The characteristics of the lensing event show that the planet is in a Jupiter-sized orbit around its parent red star. 10 CHANDRA CONFIRMS HUBBLE CONSTANT Chandra X-Ray centre A critically important number that specifies the expansion rate of the Universe, the socalled Hubble constant, has been independently determined by the Chandra X-ray Observatory. The Hubble constant is calculated by measuring the speed at which objects are moving away from us and dividing by their distance. The usual methods of estimating it rely upon measuring the apparent brightness of standard objects whose absolute luminosities ('candle-powers') are known and are supposed to have remained constant throughout the age of the Universe. Optimist have thought in recent years that the value of the constant is known to about 10%, at 72 +/- 8 km/s per megaparsec. Now, by a combination of X-ray data from Chandra with radio observations of galaxy clusters, distances have been estimated to 38 galaxy clusters ranging from 1.4 to 9.3 billion light-years. The results give a Hubble constant of 77 km/s per megaparsec, with an uncertainty of about 15%, thereby reinforcing other recent values. The implied age of the Universe is between 12 and 14 billion years. ANOTHER STORY Ohio State University Certain astronomers have suggested that the Triangulum Galaxy (M33), or at any rate one binary-star system in it, is about 15% further away from us than has been thought. That would imply that the Hubble constant should be correspondingly reduced and that the Universe could be 15% bigger and older. The astronomers studied two of the brightest stars in M33, the components of a binary system in which one star eclipses the other every five days. They determined the masses of the components, and from that they guessed the candle-power of those stars. Then the comparison between the intrinsic brightness and the apparent brightness told them how far away the stars were. It was 15% further than they expected, about 3 million light-years. The margin of error was claimed to be 6%, but there might be merit in waiting a bit before altering the Universal distance scale to suit the findings on one binary system; the star's masses may have been determined quite accurately, but their luminosities are only conjectural. BINARY PLANET-LIKE OBJECT BBC News Astronomers at the University of Toronto have discovered a companion to a 'planetary-mass object' or orphan planet -- one that has no star around which to orbit. Both objects have masses similar to those of extra-solar giant planets, usually found in orbit around a star. The researchers discovered the companion candidate in an optical image taken with ESO's 3.5-m New Technology Telescope on La Silla, Chile,and investigated it further with the 8.2-m Very Large Telescope on Paranal. Those follow-up observations confirmed that both objects are young, at the same distance, and much too cool to be stars. From theoretical models, the astronomers estimate that they have about 14 and 7 times the mass of Jupiter. The newborn pair, barely a million years old, has a separation about six times the distance between the Sun and Pluto, and is located in the Ophiuchus star-forming region approximately 400 light-years away. It is the first planetary-mass object to be resolved into a double. The existence of such a wide pair with such a small total mass and consequently weak gravitational binding sets useful constraints on theories of their origin. 11 GLIMPSES OF OBJECTS BEYOND NEPTUNE? New Scientist Astronomers combing through 89 hours of observations from the Rossi X-ray Timing Explorer think that they detected 58 minuscule trans- Neptunian objects (TNOs) between 20 and 100 metres in size. What the astronomers actually saw in the records, which were all of a distant X-ray source called Scorpius X-1, were sudden momentary dips in the X-ray brightness. The best idea that they could think of by way of explanation was that the dips, which mostly lasted only 2 or 3 milliseconds, were caused by transits of TNOs, which would be only of the order of 50 metres across if they were at the assumed distance of 43 Astronomical Units. Such objects would be much too small to detect directly with any telescope. If there were really so many of them transiting a very small X-ray source, the total number of such objects would have to be very formidable. 1000nth SUNGRAZING COMET FOUND BY SOHO Science Daily There is no formal definition of a 'Sungrazing comet,' but the term typically refers to the Kreutz-group comets, which have a perihelion distance of less than 0.01 of an Astronomical Unit. The 1000nth Sungrazer is the 1185th comet discovered in data from the SOHO LASCO or SWAN instruments (the other 185 are not members of the Kreutz group). The faint object is officially designated C/2006 P7 (SOHO) by the Minor Planet centre of the International Astronomical Union. Before the launch of SOHO in 1995 December, only some thirty members of the Kreutz group were known. All 1000 Kreutz comets are believed to be fragments of a single great comet observed in c. 371 BC by Aristotle and Ephorus, and the fragments themselves continue to fragment, making more Sungrazing comets. 20% OF MATTER USED UP Australian National University The Universe has used up about 20 per cent of its normal matter, or original fuel reserves, according to findings from a survey of the 'nearby Universe' by an international team of astronomers involving researchers at the Australian National University. The survey suggests that about 20 per cent of the normal matter or fuel that was produced at the Big Bang 14 billion years ago is now in stars, a further 0.1 per cent lies in dust expelled from massive stars (and from which solid structures like the Earth and its people are made), and about 0.01 per cent is in super-massive black holes. The survey data, which constitute the 'Millennium Galaxy Catalogue', were gathered by telescopes in Australia, the Canary Islands and Chile, and include over ten thousand giant galaxies. According to the survey leader Dr Simon Driver of St Andrew's University, the remaining material is almost completely in gaseous form lying both within and between the galaxies, forming a reservoir from which future generations of stars may develop. The catalogue has estimates of the distribution of each galaxy's stars between its central bulge and its surrounding disc-like structure. Roughly half of the stars appear to reside in bulges and the other half in discs. FOUR NEW MILKY WAY SATELLITES New Scientist Four new satellite galaxies of the Milky Way have been discovered, bringing the total known to about 20. The pace of new discoveries suggests that many more such satellites remain unknown. The satellites are dwarf galaxies a few hundred to a few thousand light-years across. The tiny galaxies are thought to be the building blocks of large galaxies, such as our own Milky Way which is about 100,000 light-years across. 12 The small galaxies are faint and difficult to observe behind the throngs of foreground stars in the Milky Way. Just two years ago, only 10 satellite galaxies were known, with the exact classification of some objects in dispute. Now, thanks to new observing techniques and detailed sky maps such as the Sloan Digital Sky Survey (SDSS), that number has doubled. Astronomers use SDSS to look for the particular types of stars expected to lie in dwarf galaxies, then detect the dwarfs as slight 'overdensities' of those types of stars. The four new discoveries were made by astronomers at the University of Cambridge. Named after the constellations in which they were found -- Coma Berenices, Canes Venatici II, Hercules, and Leo IV, all of them are between roughly 100,000 and 500,000 light-years away. The largest and smallest are Hercules and Coma Berenices, which are about 1000 and 200 light-years across, respectively. Like most of the other dwarfs discovered by SDSS, the new finds are much smaller and fainter than the 10 dwarfs that were known previously. HIGH-ALTITUDE CLOUDS SEEN ON MARS Science Today Until now, scientists had been aware only of the clouds in lower reaches of the atmosphere. Mars Express has now seen a fleeting layer of clouds, most likely composed of carbon dioxide. at an altitude between 80 and 100 kilometres. The new high-altitude cloud layer may have implications for landing on Mars, as it suggests the upper layers of Mars' atmosphere may be denser than was previously thought. That will be an important piece of information for future missions if they rely on friction in the outer atmosphere to slow down spacecraft (a technique called aerobraking), either for landing or going into orbit around the planet. SUPERNOVA CAUGHT IN THE ACT Astronomy.com A weak but abnormally long-lasting gamma-ray burst (GRB) has given astronomers an unprecedented start-to-finish view of an exploding star. Ground- and space-based telescopes studied the blast in detail at gamma-ray to radio wavelengths. Scientists now suspect that such weak bursts may outnumber more powerful ones by as much as 10 to 1. Usually, such events are not detected until after the supernova has brightened substantially at optical wavelengths, many days after the initial explosion, but on this occasion astronomers were able to study the remarkable event from the very beginning. On February 18, the Swift satellite sensed a rise in gamma rays from the constellation Aries. Within 20 seconds, the spacecraft reported the burst's location to astronomers and slewed its instruments towards the source. The burst lasted about 35 minutes -- about 100 times longer than typical bursts associated with supernovae. It was also just 1 per cent the brightness of GRBs seen in the distant Universe, which places it in a sub-class known as X-ray flashes. After two-and-a-half minutes, Swift's telescopes identified the blast's X-ray and ultraviolet counterparts. They coincided with a dwarf galaxy about 500 million light-years away. That places the burst some 25 times closer than typical GRBs. On February 20, two days after the GRB, a brightening type Ic supernova began to be seen. IMPACT LANDING ENDS SMART-1 MISSION ESA A small flash was detected on the Moon as the SMART-1 spacecraft crashed into it on the night of September 2. The impact took place in an area of the Moon in the vicinity of Lacus Excellentiae, unilluminated by the Sun but near the terminator, at a grazing angle of between 5 and 10 degrees and a speed of about 2 kilometres per second. The planned impact concluded a successful mission that, in addition to testing innovative space technology, had been conducting a thorough scientific exploration of the Moon for about a year and a half. 13 SATELLITES COULD NAVIGATE BY X-RAY STARS New Scientist Future satellites could use X-ray-emitting stars, rather than GPS signals, to get their bearings, according to plans by the US military. X-ray navigation technology would be less vulnerable to enemy interference than GPS, and could also be used far from Earth to help interplanetary space probes keep track of their positions. The X-ray beacons would be pulsars, rapidly spinning stars which emit regular pulses of X-rays as they spin. Each pulsar has a unique frequency and location in the sky. Locking onto any one of them would tell the satellite which direction is which in the sky. The signals from several pulsars could be exploited to determine a spacecraft's position and velocity in the same way as by GPS, but in principle it would be simpler because the beacons are fixed. The pulsar signals are ideal for the purpose, because their frequency stability rivals that of atomic clocks. A further useful feature of the system, from a military point of view, is that X-ray detectors are not easily blinded by lasers which might be aimed at them maliciously, nor by being pointed accidentally at the Sun, unlike the visible-light cameras used to track ordinary stars. BIG BANG'S AFTERGLOW FAILS SHADOW TEST Science Daily The apparent absence of shadows where shadows were expected to be is raising a question about the faint glow of microwave radiation that has been regarded as proof that the Universe was created by a 'Big Bang'. In a finding sure to cause controversy, scientists at the University of Alabama found a lack of evidence of shadows from 'nearby' clusters of galaxies in new, highly accurate measurements of the cosmic microwave background. A team of scientists used data from the Wilkinson Microwave Anisotropy Probe to scan the microwave background for shadows caused by clusters of galaxies. IIf the background really originated in the Big Bang fireball, then it should appear to come from further away than anything else that is observable, and massive clusters of galaxies should all cast shadows on the background. The principle of shadowing is elementary: if you see a shadow from a cluster, it means that the radiation comes from behind it, but if you don't see a shadow, then you have something of a problem. Among the 31 clusters that were studied by the team, some appear to show a shadow effect and others do not. Taken together, the data show a shadow effect about one-quarter of what was predicted -- an amount roughly equal to natural variations previously seen in the microwave background across the entire sky. 14 MARS ROVER NEARS CRATER NASA The Mars rover Opportunity is closing in on what could be the richest scientific findings of its mission so far. Within the next week the robotic geologist is likely to reach the rim of a crater bigger than any it has previously visited. The crater, known as Victoria, is approximately 750 m in diameter and 70 m deep. Images from the Mars Global Surveyor orbiter show the crater walls to expose a stack of rock layers approximately 30 to 40 metres thick. Opportunity will send back its initial view into the crater as soon as it gets to the rim, and its controllers hope to use its observations from various points around the rim to try to plot a route for it to enter the crater. The twin rovers have been exploring landscapes on opposite sides of Mars since 2003 January. Originally, their missions were supposed to last three months, but both are still investigating Mars' rocks, soils and atmosphere after more than ten times as long. Opportunity works in a region where rock layers hundreds of metres in thickness cover older, heavily cratered terrain. PLANET OR FAILED STAR? STSI Astronomers using the Hubble telescope have photographed one of the smallest objects ever seen around a normal star beyond our Sun. With 12 times the mass of Jupiter, the object, CHXR 73 B, is small enough to be a planet, but it is also massive enough to be a brown dwarf, a failed star. There is at present no consensus on how to decide which objects orbiting other stars are truly planets. Hubble discovered the object while conducting a survey of isolated brown dwarfs. CHXR 73 B is 19.5 billion miles from its red-dwarf primary, roughly 200 times farther than the Earth is from the Sun. At 2 million years old, the star is very young when compared with the Sun. Young brown dwarfs are brighter than older, cooler ones, so they can be seen at lower masses, where older dwarfs would be undetectable. Hundreds of brown dwarfs have been found in our Galaxy since the first ones were discovered about a decade ago. Most of them are alone in space and not orbiting stars. There is interest in studying young star systems in an effort to understand how small bodies formed. Planets are supposed to form in circumstellar discs of dust and gas, but such discs are normally not big enough to cover the region in which CHXR 73 B is seen; even if the red-dwarf primary possesses a disc there would not be enough material at that distance from it to create a planet. Theoretical models show that giant planets like Jupiter form no more than about 3 billion miles from their stars. PLUTO ASSIGNED A NUMBER AND XENA RENAMED ERIS Space.com Pluto has been given a new name to reflect its new status as a dwarf planet. On September 7, the former 9th planet was assigned the asteroid number 134340 by the Minor Planet Center. The move gives_expression to the International Astronomical Union's recent decision to strip Pluto of its planethood and place it in the same category as other small Solar-System bodies with accurately known orbits. Pluto's satellites, Charon, Nix and Hydra are considered to be part of the same system and will not be assigned separate asteroid numbers, according MPC director emeritus Brian Marsden. Instead, they will be called 134340 I, II and III, respectively. There are currently 136,563 asteroid objects recognized by the MPC; 2,224 new objects were added last week, of which Pluto was the first. 15 The name Xena by which the body formally designated 2003 UB313, whose size (slightly larger than Pluto's) precipitated the recent concern over the definition of planets, is another casualty of recent IAU decisions -- the object has been assigned the asteroid number 136199 and officially named Eris. Eris is the Greek goddess of discord, so the name hints at the troubled ordination of the newly-discovered body. One of Eris' discoverers, Michael Brown of the California Institute of Technology, said that the new name was "too perfect to resist". Eris' moon has been named Dysnomia, after Eris' daughter -- the spirit of lawlessness -- in Greek mythology. Eris joins Pluto and Ceres in the new category of 'dwarf planets.' Six Months On ... and the Sun is still there! It is coming up to 6 months from the 2006 total Solar eclipse March 29) so the memory bank is being returned to. This was a cruise in the Med. taking in a wealth of archaeology on the way to Libya. There were several friends and colleagues on board the MV Perla together with some 770 others. But why do "experienced, hard-bitten" astronomers, amateur and professional alike go for the few minutes or even seconds of the darkening of the Sun? My first experience of 1991 July 11 may be likened to train-spotting/knocking off a "first" event. This tear-dripping event of the Black Moon surrounded by the Sun's corona was seen from the tip of the Baja Peninsula, San Jose del Cabo. A total Solar eclipse is virtually indescribable in words and one of the best attempts I have read is from a late 1991 Sky & Telescope - moving stuff. Solar totality is likened to a spiritual event, it is certainly primeval in perception. Several who were shattered not to view the 1999 Aug 11 totality due to cloud cover may have been impressed by the apparent midnight conditions during daylight hours but the dark side of the Moon and the solar atmosphere were absent. Back to the near 800 passengers on route for the darkness. At Manchester Airport and thrown into the chaos of a "punch-up" with a crazed thug we then met with more polite types, other astronomers from local societies and professionals like the WYAS President Prof. David Hughes. Later on board the MV Perla moored at Heraklion (Crete) we came across lots of other friends and acquaintances from all over the UK. One of my long standing variable star friends Dr. Rhona Fraser (Inverness) dashed around a corner with Jill, her cabin mate, and soon the chat became completely irrelevant to other non-vs orientated types. There were a few "strange" astro creatures, those who could be the subject of one's nightmares or part of an Alice Cooper clan. (Apologies to any fans thereof). Eclipse day started with a 02h ship's awakening then a departure from Benghazi harbourside on coaches (23 in total) for a 500 mile trip to the observing site close to the ground centre-line in the Jula Oasis. Stress, trauma, paranoia, expectation - anxiety, deep seated "rumbles" - please reader, try and relate to one who has shunned away from long distance coach travel since he said 20 years ago he would never use this form of transport. But it was impossible not to participate in this Libyan and Greek expedition if totality was to be seen. Cornwall 1999 was a sombre reminder of disappointment and failure. Things and folks go through the mind as it plays tricks in deserts - flat, boring ochre sand for miles and miles, the optical lake near the horizon, another jolt as the Egyptian (El Joker company) coach suspension clattered over another dead camel. No, I joke, but this is an attempt at conveying reality. The eclipse team did their best to eat, part sleep and keep each other in the right frame of mind. Mark chats about his last holidays in Europe, Jill relates her enjoyment of opera, "Einstein on the Beach" seems relevant, Rhona discusses recent intricacies of a variable star, Alex and Harry my walking chums of many years hark back to happier times in a sodden tent on a Glencoe trip! 16 Anything to pass the time comfortably, audio tapes played, cameras checked, another doze is broken up as the driver honks to a fellow coach - a mindless tune like "Close Encounters speak" from one alien to another? It is also the tiny event that picks up the spirit. At a service station toilet stop where all the coaches had to refuel again, we lined up waiting for the long "loo" line. The small cafe area had a cooler with Pepsi bottles - and cans of "Booze" - in Libya!? Some of the party could not resist. Would the security put us in the local "clink", I think not. Part and parcel of the Libya tour and not only the eclipse site involved keeping people safe and politics insisted we had proper armed security with several X-Men look-alikes hounding around. So the convoy of coaches had police trucks at front and rear, if one coach had to refuel or break down, the convoy had to stop. At major road junctions of which there were few the main road was blocked by another police/army crew, and through small towns nearer Benghazi police were showing a presence. Our coach no. 13 broke down so we had to use the spare one, an equally dismal El Joker. With several other delays on the outward trip the tented, international site was not reached since the road was blocked by a multitude of other vehicles and camels, traders, military and the Brits! Helicopters hovered in the distance into the huge site, TV company wagons were extremely modern in comparison to other transportation. Where was Kate Adie and her team? We had been asked not to show any obvious cultural allegiances in the form of flags or logos but I did wear my Yorkshire CCC sunhat! About 1.9 km short of the area that Explorers had defined for the observation site, and with only 20 minutes to go for first contact, most of the 800 quickly took themselves off into a once virgin sand 'scape now littered with cars, trucks, assorted astronomers and other eclipse cases, it had the air of a rock festival. And a countdown was now on for the main players were coming to the stage. Describing a total eclipse in words is very hard but John Mason's pre eclipse account was magnificently near the actuality - the man is a minor genius! An eerie shimmering on the sand as thousands of dark sinuous snakes washed their way prior to first contact - shadow bands. A superb diamond ring broke out near a set of Baily's Beads with the pink prominence at about 11o-clock. The five or so coronal streamers to the left, three to the right, in binocs a review of magnetic strewn hairs from the polar areas and Venus plus Mercury in the twilight dark sky. And the Dark Circular Hole that is the Moon in a unique situation. People gasping, people praying folk just in silent awe. Others recorded a personal record in one's experiences. On the Moon's departure a host of pink prominences and a wonderful double diamond and shadow bands yet again. Wow! and biting of lips! The 4 minutes of totality was worth the effort and hardship, then 8.5 hours on the journey back to the boat was similar if more desperate than the outward leg. Photos had been taken, happy snaps of our eclipse site and observers, brief encounters with Libyans who had travelled to the site. I had shown a bunch of lads the partial phases which they photo'd using a mobile through my visual scope. Rhona had been presented with a gift of an embroided gold coloured hat made by the group who had been praying nearby. Mark had lit up his celebratory cigar, Harry talked with local scouts who unbelievably had heard of Liverpool FC, probably not of Doncaster FC. Alex announced that this had been one of the best eclipses he had seen. Ray and Chris were happy and smiling not that far away; the Marchant family were not in sight to be asked "how was it for you?". Back on the ship the day after, this question was asked and answered many times. Other astronomers on site were really too happy to be true as they started packing away the kit and chatting over the spent scene. Several whose first successful total eclipse this was like Jill stayed for the whole partial phases - quite right. The eclipse day had taken 23 hours when the cabin door was opened and sleep came easy. Wednesday 2006 March 29 in the Libyan Desert, a tiring but very special day. Melvyn Taylor, 2006 April and September. 17 18 19 20 21 22 . 23 24 25