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The SOCIETY for POPULAR ASTRONOMY
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Electronic News Bulletin No. 188 2006 January 8
=====================================================


Here is the latest round-up of news from the Society for Popular
Astronomy. The SPA is Britain's liveliest astronomical society, with
members all over the world. We accept subscription payments online
at our secure site and can take credit and debit cards. You can
join or renew via a secure server or just see how much we have to
offer by visiting http://popastro.c.topica.com/maaenlVabnmwkcixLLVb/

Philip's, a publisher of astronomy books and planispheres for the
amateur astronomer, is sponsoring this bulletin. For information on
Philip's title see the end of this bulletin.


TAURID LUNAR IMPACT
By Alastair McBeath, SPA Meteor Section Director

Right in the midst of the Taurid fireball spell on Earth, reported in
recent
ENBs, on November 7, an Earth-based NASA telescopic imaging
programme run by researchers Rob Suggs and Wes Swift at the Marshall
Space Flight Center in Alabama, detected a magnitude +7 impact flash in
Mare Imbrium, which was probably due to a large Taurid meteoroid.
NASA suggested the impactor may have been around 12 cm in size,
which, at a typical Taurid velocity, around 27 km/sec, would have
created
a crater approximately 3 metres wide by 0.4 metres deep, far too small
to
be seen from Earth unfortunately. Even the Hubble Space Telescope can
distinguish objects on the Moon no smaller than 60 metres or so in size.

For notes, discussion, and the essential website addresses (including
links
to where you can find predictions for suitable times to hunt for other
lunar
impacts later this year, if you have access to a suitable telescope and
imaging gear), see the "An Explosion on the Moon" topic on the SPA's
General Chat Forum, at:
http://popastro.c.topica.com/maaenlVabnmwlcixLLVb/

The first lunar impact flashes were detected by Earth-based video
systems during the Leonid storm in 1999, and a few others have been
found since for the Leonids and Perseids, with others suspected but not
confirmed. This is NASA's first successful imaging of such an event,
though their records of lunar impacts go back to the Apollo seismographs
left on the Moon from 1969-72. In late June 1976, these recorded a
series of large impacts believed to have come from one of the Taurid
showers' daytime twins, the Beta Taurids, during an earlier 'swarm'
return
from this set of meteoroid streams.


PRELIMINARY DECEMBER METEOR RESULTS
By Alastair McBeath, SPA Meteor Section Director

December's weather over Britain seems to have been about as unhelpful
as it could be across the expected Geminid and Ursid maxima, around
December 13-14 and 22 respectively, judging by the lack of positive
results in so far.

In the UK, only Mike Dale in Edinburgh and myself have reported having
any luck in spotting some Geminids through the clouds near the peak as
yet, along with Jay Brausch in North Dakota, USA. Mike had some good
clear skies for a time in the early morning hours of December 13-14, and
spotted healthy Geminid numbers. Enrico Stomeo in Italy managed a
good run of video observing then too, and recorded two peaks in
Geminid activity (allowing for the radiant's varying elevation), a
lesser one
at about 22h30m UT, and a stronger one towards 03h20m UT, although
his video counts were very good all night, as we would expect from this
shower, even with the bright Moon. The peak was due between 02h-07h
UT then (see ENB 186), so the stronger video peak would certainly fit
that pattern.

The Ursids seem to have been more uniformly cloud-bound from Britain.
Fortunately, regular Section correspondent Rich Taibi in Maryland, USA,
has kindly forwarded his own visual results, plus those of fellow
Americans Paul Martsching (Iowa), Bert Matous (Kansas) and Bill
Godley (Oklahoma), with some preliminary radio notes from observers
Michael Boschat (Nova Scotia, Canada) and Esko Lyytinen (Finland),
plus Radio Meteor Observation Bulletin Editor Chris Steyaert. Visual
activity was generally low on December 22 over the USA, but some of
the European radio results indicated a possibly strong peak around
09h-11h UT then. Whether this was due to the Ursids, an unknown
shower, or perhaps some non-meteoric interference, is not yet clear.
Oddly, the visual data from America did not confirm anything unusual
from the Ursids during this interval, which might suggest a lot of faint
to
very faint meteors were responsible for the radio "peak", if that was
due
to meteoric activity. A fuller investigation will follow when all the
December radio results are in.

Anyone with data still to submit from December is most welcome to do
so. Advice on what to report and where to can be found via the SPA
meteor homepage at: http://popastro.c.topica.com/maaenlVabnmwmcixLLVb/ .


OCCULTATION OF BY CANCRI* (SAO 98054) BY SATURN
January 25 2006 18h 05 UT - 20h 50m UT
By Jon Harper Occultation Section SPA

This event is going to take place during the evening of Wednesday,
January 25th, a few days before Saturn's 2006 Opposition, and should be
quite spectacular telescopically, particularly as SAO 98054, at m(v) 7.9
is a little brighter than Titan. The occultation presents an interesting
challenge for both amateurs who use CCD's for imaging and also for
those who sketch what they see. It is of course reasonably rare for a
star
of this magnitude to be occulted by the Saturnian System, and I do hope
that you will want to take up the challenge

The occultation had been noted last summer by Dr Tolis Christou of the
Armagh Observatory in Northern Ireland, but very little information has
been distributed as yet.

My own predicted data relating to the event for central UK (using Guide
8 software) is as follows:

Occultation by Ring A : 18h 50m (all times = UT)
Reappearance in Cassini's Division: 19h 01m
Disappearance behind Ring B: 19h 06m
Possible brief reappearance in Cassini's Division prior to occultation
by
Saturn's disk: 20h 03m.
Reappearance from behind the disk in the vicinity of Saturn's South Pole
(PA = 166°) 20h 50m

I am encouraging all members of the SPA to attempt observing this
interesting occultation and hopefully some of you may try imaging it,
especially during the Cassini "window" around 19h 01 - 19h 06

*Note about BY Cancri ( SAO 98054)

This star lies at the edge of the 'Beehive Open Cluster' M44, and is a
Delta Scuti type variable star, with a small amplitude of only 0.01. It
is a
white star of spectral type A5, and so should show up nicely against the
dusky tint of Saturn's South Polar region after the star's reappearance
at
20h 03m.

I have produced a chart showing the appearance of Saturn and the
position of BY Cancri when "passing through" Cassini's Division around
19h 03 UT. If you require the GIF of this please send an e-mail
requesting it. Jonvran@aol.com


PULSAR HAS COMET-LIKE TAIL
Italian National Institute of Astrophysics

Scientists in Milan using the Chandra X-ray Observatory Archive have
discovered that Geminga, one of the closest pulsars to Earth, leaves
in its wake a comet-like trail of high-energy electrons as it travels
through space at 120 km/s. The discovery follows the discovery in
2003 with XMM-Newton of Geminga's twin X-ray tails stretching for
billions of kilometres. Together, those observations provide some
insight into the contents and density of the interstellar 'ocean' that
Geminga is ploughing through, as well as the physics of Geminga
itself. Not only is Geminga close, only about 500 light-years from
Earth, it is cutting across our line of sight, offering a spectacular
view of a pulsar in motion. Only about a dozen other such radio-quiet
isolated neutron stars are known, and Geminga is the only one with
tails and trails and copious gamma-ray emission.


SATELLITES OF URANUS
IAU

The following names have been approved for recently discovered
satellites of Uranus:

Uranus XXII Francisco = S/2001 U 3
Uranus XXIII Margaret = S/2003 U 3
Uranus XXIV Ferdinand = S/2001 U 2
Uranus XXV Perdita = S/1986 U 10
Uranus XXVI Mab = S/2003 U 1
Uranus XXVII Cupid = S/2003 U 2


RINGS OF URANUS
IAU

Astronomers have confirmed the existence of two new rings of Uranus,
designated R/2003 U 1 and R/2003 U 2. Both are faint, dusty rings
orbiting well beyond Uranus' previously known ring system.
R/2003 U 1 peaks in brightness at 97 700 km from the centre of Uranus,
coinciding with the orbit of Uranus XXVI (Mab), which is almost
certainly the ring's primary source body. The ring has a broad
triangular profile, with an inner limit at 86 000 km -- near the
orbit of Uranus XV (Puck) -- and an outer limit at 103 000 km.
R/2003 U 2 peaks in brightness at 67 300 km, where no known moon
exists. It too has a triangular profile, terminating near the orbits
of Uranus XII (Portia) on the inside and Uranus XIII (Rosalind) on the
outside.


COMET DUST SAMPLES
Reuters

A sample of comet dust collected by a space probe is scheduled to
parachute down to Earth on January 15. The spaceship Stardust is
coming to the end of its seven-year, 2.9-billion-mile round-trip
mission to Comet Wild 2, catching dust that could give astronomers
clues about how the planets formed some 4.5 billion years ago.
Stardust went halfway to Jupiter to get close to Wild 2, catching
hundreds of comet-dust particles in a collector that looks something
like a large tennis racket with a round metal ice-cube tray where the
strings would be. Inside the collector's ice-cube-size compartments
is a material called aerogel, a low-density substance that is 99.9
per cent air, which acted to capture grains of dust emitted by the
comet. Stardust's collector got within 147 miles of Wild 2, close
enough to be bombarded by millions of cometary particles, and to catch
hundreds of them.

NASA officials have stressed that the Stardust capsule is extremely
rugged and said that they are prepared for the possibility of a hard
landing so the samples will not be damaged before they can be studied.
A previous NASA probe called Genesis crashed to Earth in 2004 when its
parachute failed to open. That craft had been on a three-year mission
to collect solar ions, some of which were recovered by scientists even
though the capsule was destroyed.


MARS NOT SO WET
NASA

When Opportunity touched down on a part of Mars called Meridiani
Planum, it came across 'geology' that looked tantalizingly like the
product of standing water. The researchers running the mission wrote
that "surface conditions at Meridiani may have been habitable for some
period of time in martian history". Opportunity found a scattering of
tiny round pebbles that looked as if they had formed in water, and
rectangular holes in the crater wall that could have been left by
dissolved mineral crystals. There were also ripple patterns in the
rock, and a layering that looked as if sediments had settled out of
water.

Now, geologists from Arizona State University suggest an alternative,
dry, explanation that all these features were produced by a surge of
rock, minerals and brine caused by a meteorite impact, along with
chemical changes from groundwater -- but no pools. The scientists
point out that any water in the area would have left channels, deltas
and other shoreline features that Opportunity has not found, and they
add that briny, acidic water would dissolve through alkaline basalt
rock, not create puddles. The layered features found by Opportunity,
interpreted as sedimentation from water, are also seen on Earth, but
in some cases they are attributed to surges of material from meteorite
impacts.

Planetary scientists at the University of Colorado, Boulder, provide
another arid explanation, suggesting that the mineral deposits are
volcanic ash that has reacted with small amounts of acidic water and
the volcanic gas sulphur dioxide. The watery interpretation fails,
they argue, because the sediments do not contain enough of some
metals, such as calcium, magnesium and iron, that ought to be in rocks
laid down by water.


ACETYLENE AND HCN FOUND
NASA

The Spitzer space telescope has discovered acetylene and hydrogen
cyanide in the dust orbiting around a young star called IRS 46 in
Ophiuchus, about 375 light-years from Earth. That constellation
harbours a lot of gas and dust in the process of condensing into
stars. Like other young stars there and elsewhere, IRS 46 is
encircled by a rotating disc of gas and dust that might ultimately
clump together to form planets. Spitzer's infrared spectrometer found
in it the spectral signatures of large amounts of acetylene and
hydrogen cyanide, as well as carbon dioxide. The temperature of the
gas indicated that it is probably about the same distance from the
star as the Earth is from the Sun. The team observed 100 other
young stars but found no other similar ones. News items have
suggested that the presence of such very simple organic compounds as
have been seen in IRS 46 somehow implies that life will soon start up
there, but in actual fact there is an enormous gulf between the
existence of simple compounds and the existence of even the most
primitive life.


FIRST GLIMPSE OF NEW STARS
AP

Astronomers using the Spitzer telescope have discovered in a nebula in
Monoceros a cluster of stars less than 100,000 years old. Scientists
at the University of Arizona say that the star cluster, which is 2,500
light-years away, gives them the first glimpse of newborn stars acting
just as predicted -- patterned geometrically and spaced according to
density, temperature and gravity. The Spitzer images reinforce
British astronomer James Jeans' early-1900s gravitational-collapse
theory.


PHILIP'S NEW TITLES:

Philip's The Sky at Night Volume 2 is the latest volume in Sir Patrick
Moore's series of essays written to accompany the BBC television
series of the same name. It tracks developments in astronomy,
astrophysics and space exploration in the period from 2001 November
to 2005 March -- £9.99
Philip's Stargazing 2006 by Heather Couper and Nigel Henbest.
Stargazing 2005 was a popular addition to Philip's astronomy list last
year, and the 2006 edition of this month-by-month practical guide to
the changing night sky is expected to be equally well received. - £6.99
Published last month:
Philip's Solar System Guide by Peter Grego contains an abundance of
information and images, and is a practical and colourful introduction to
our corner of the Universe. It describes how to observe not only the
planets but also the Moon, Sun, comets, meteors, asteroids and other
objects found within our Solar System -- £9.99
Philip's Solar System Observer -- a new pack for the amateur
Solar-System observer. It contains three items for exploring
and enjoying our corner of the Universe: Philip's Solar Observer's
Guide, Philip's Map of the Solar System and Philip's Solar System
Phenomena poster -- £12.99
For more information on those and other Philip's titles please visit
www.philips-maps.co.uk or call 020 7644 6935 for a catalogue.


Bulletin compiled by Clive Down

(c) 2006 the Society for Popular Astronomy


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