WADHURST ASTRONOMICAL SOCIETY
APRIL NEWSLETTER 2008
INDEX: MEETINGS, OTHER NEWS, CONTACTS
A talk given
by Konrad Malin-Smith at the March meeting
The meeting was
opened by Phil Berry welcoming back Konrad Malin-Smith whose talk this time was
about the Magellanic Clouds visible from the southern hemisphere. Konrad began
his illustrated talk with an astro-photograph of the area around the earth's
celestial south pole.
There is no
visible star that marks the pole like Polaris in the Northern sky but in this
photograph we could see the Southern Cross, Alpha Centauri and the Large and
Small Magellanic Clouds.
sixteenth century, a Portuguese maritime explorer called Magellan was in the
service of the Spanish Crown and was asked to find a westward route via the tip
of South America to the Spice Islands in Indonesia.
Magellan had visited the islands previously but by approaching from the
opposite direction across the Indian Ocean.
purposes, he considered the South Celestial Pole to lie somewhere between the
two misty clouds visible in the night sky.
These were to be named the Large and Small Magellanic Clouds in his
memory after he had fallen out with the locals of Mactan and killed.
discovered that the clouds are not part of the Milky Way but are in fact
irregular dwarf galaxies. The next
diagram Konrad showed us was of the Milky Way around which orbited material that
formed the two clouds and by observing Cepheid Variables in them and measuring
their proper motion it has been calculated that the clouds are in a huge orbit
around our galaxy, taking 2.2 billion years to complete one orbit.
The Large Magellanic Cloud is at a distance of about 175,000 light years.
It has also been
found that there is a stream of atomic hydrogen linking the orbit of the clouds
with the Milky Way.
The next few
slides showed a trip Konrad had made to Perth in Australia.
Using a Potterton Gas boiler clock drive, they were able to track their
telescopes and take several film images. From
here, Sirius was more like a powerful searchlight and familiar Orion was now
One of the images
was of the Large Magellanic Cloud (LMC) taken with a 15-minute exposure using
1000 ISO film. The image revealed
much of the structure of the cloud with several blue stars ionising gas clouds.
One of the main
features of the Large Magellanic Cloud is NGC 1910, a large star cluster with a
definite "S" shape. Inside
this cluster is a variable star called S Deradus, which is a million times
brighter than our own Sun.
Konrad showed RR
Lyra stars, which are standard variables rather like Cepheid variables but far
fainter, being used to calculate the distance of the Small Magellanic Cloud
(SMC) as 210,000 light years away. This
cloud is much less evolved than our own galaxy and contains far more hydrogen
than might be expected and we saw NGC 346 viewed through a hydrogen-alpha filter
to reveal its delicate structure.
The SMC is rather
like a huge tube and using radio astronomy, it has been shown that the SMC is
spinning. If it weren't spinning
all the stars would collapse into the centre.
This has also been shown to be the case with the LMG as well.
At this point,
Konrad described how The Small Magellanic Cloud became important in measuring
A certain type of
variable star had puzzled astronomers for some time.
These were known as Cepheid Variables after Delta Cephei in the
constellation of Cephus.
In 1908 Henrietta
Leavitt joined Harvard University in the USA and for a number of years studied
Cepheid Variables in the SMC from an observatory in the Peruvian mountains,
taking thousands of photographic plates.
that their period of fluctuation was related to brightness and since they were
all in the same cloud it was reasonable to think they were at similar distances
From this she
worked out a mathematical relationship of brightness against period although no
Cepheid variables were close enough to the Sun to calculate their distance using
Hertzsprung who, in 1913 suggested using the average proper motion of Cepheid
variables near the solar system since by then there were enough photographic
plates taken over many years. He
calculated, incorrectly as it happened, the distance of the SMC as 30,000 light
used Cepheids as distance indicators and determined the size of the Milky Way as
300,000 lys, although later corrections brought this to 100,000 light years in
Konrad's introduction to the Magellanic Clouds, he described a supernova in the
LMC that was observed to take place in 1987, the closest in nearly 400 years. It has been named SN1987A.
looked at previous images of the same area it was found that the progenitor star
was a blue super giant around which was a bright ring of material created from
its stellar wind.
It is now
understood that the plane of this ring slopes back as seen from earth.
It was ionised by the ultra-violet flash from the supernova explosion and
consequently began emitting light once the UV reached it several months after
This light from
the nearest part of the ring was detected on earth.
As time passed this light spread round to eventually ionise the entire
ring, the delay being caused by the enormous distances involved around the ring
and the speed of light.
The size of the
ring is known, and using basic trigonometry the distance to SN1987A has found to
be about 171,000 lights years.
An excellent talk
as one has come to expect from Konrad.
The Committee met
on Monday 31st March when the Treasurer announced that at present we have 28
paid-up members, which are down on last year, although the funds remain healthy
with £554-62 in our current account and £1,147-73 in the reserve account.
It was proposed
that we try and share member's skills and with this in mind the "Help
List", which is available at each meeting could be partly used for this
Phil Berry has
written a comprehensive letter on behalf of, and signed by the Committee with
regard to objections to the proposed evening lighting of the Wadhurst Tennis
Club. This letter has been
forwarded to Wealden District Council.
April 2008 Greg Smye-Rumsby gives a talk he has entitled "Astronomical
Bits and Bobs".
Greg is a member
of the Orpington Astronomical Society and in addition narrates presentations at
the Greenwich Planetarium. He is
also well known through his many contributions to the Astronomy Now magazine.
begins at 1930 although members are invited to arrive anytime after 1900. This is a good time to exchange ideas and discuss problems.
MEETINGS & EVENTS
May 2008 Our own Brian Mills who contributes the excellent Sky Notes each
month is giving a talk about "Occultations".
During June: A trip is being arranged to visit the Great Transit Circle at Greenwich Observatory. This will be either Friday 13th or 20th of June.
Wednesday 18th June 2008 Because this is one of the shortest nights of the year and in recent years this has become a members evening when we can bring telescopes, binoculars and other aids to amateur astronomy to chat about their use and discuss problems. There will also be a short video on an astronomical subject. More info. nearer our June meeting.
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FOR THE CURRENT YEAR
session of the Society began on 1st of January.
Mike Wyles, is ready to accept subscriptions, which are the same as previous
years at £15 per member and £20 for two members in the same family.
Mike prefers to
receive a cheque payable to "Wadhurst Astronomical Society" although
he will willingly take cash. If it
is more convenient, subscriptions can be sent direct to him at:
Mr. M. Wyles, 31
Rowan Tree Road, Tunbridge Wells, Kent
the monthly meetings, Phil Berry has introduced a clipboard with a sheet headed
"Help List" intended for anyone asking advice.
It has been used successfully and members are reminded to use the list as
much as possible. It can be useful
for discussion purposes as well as hopefully providing answers.
CLOSURE OF JODRELL BANK
Bank was first used by Manchester University for astrophysics in 1945 and since
then has contributed considerably to astronomy, particularly after the building
of the Lovell stearable radio telescope in 1957.
early achievements are well documented but more recently it has obtained
distinction worldwide through its research in Long Base Line Interferometry with
ongoing MERLIN: Multi-Element Radio Linked Interferometer Network.
work that cannot be done successfully at present elsewhere is being made on
Pulsars, Background Radiation and astro-chemistry.
(The Southern Area Group of Astronomical Societies) has sent the following note:
Bank costs approximately £2.5 million a year to operate.
Putting this into perspective, Cabinet Ministers are said to have claimed
that amount in expenses during 2007.
article below gives some information:
you feel strongly about the proposal and its significant implications for damage
to UK Radio Astronomy's high profile around the world, we have been asked to
encourage people to write to their local MPs, local newspapers and national
everyone will have the time to do that. However
I would urge you to sign the Downing Street petition. (The recent Road Charging
petition gained a massive number of signatures and appears to have affected
government policy, so this is worth the small effort)
link to the PM petition is here:
second petition also aiming to reverse funding cuts proposed for UK Radio
Astronomy has also begun. This
could have the effect of splitting the signatures between the two petitions, so
you may wish to sign both petitions to ensure maximum impact.
second petition is:
NOTES FOR APRIL
will only become visible at the very end of the month, very low down in the
north west after sunset. Remember never to sweep this area of the sky with
optical aid until after the sun is below the horizon. As I mentioned in the
February sky notes, the best evening views of Mercury this year will occur in
too close to the Sun for observation this month.
lies in the constellation of Gemini (the twins) as its magnitude continues to
decrease to +1.2. By the end of the month it will set at around 01.30 (02.30 BST).
a morning object low down in the south east at magnitude -2.2 in the
constellation of Sagittarius (the archer). By the middle of the month it rises
at around 02.00 (03.00 BST).
still in Leo (the lion) and is excellently placed for observation at magnitude
+0.5. It is on view almost all night, setting at around 03.45 (04.45 BST).
Phases of the Moon for April
|New||First Quarter||Full||Last Quarter|
The Lyrid meteor
shower is active from April 19th to 25th with maximum occurring on the 22nd. The
radiant in the constellation of Lyra (the harp) is almost circumpolar from the
UK, but sadly this year the moon is just past full at the time of maximum when
we would expect a zenithal hourly rate (ZHR) of around 10 meteors per hour.
occultation on March 14th that I mentioned in the last newsletter turned out to
be a non-event due to almost total cloud cover. Thanks to Geoff who had agreed
to accompany me to the sites I had chosen near Headcorn.
Just a reminder
for anyone interested, that the annual event at Kelling Heath in Norfolk takes
place from Friday 4th April to Sunday 6th April.
There is a
daylight occultation of Mars by the Moon on May 10th at 13.43 BST.
Wildlife from Space
It's 10 o'clock,
and do you know where your Oriental Honey Buzzard is?
whereabouts of birds and other migrating wildlife across thousands of miles of
land, air, and sea is no easy feat. Yet to protect the habitats of endangered
species, scientists need to know where these roving animals go during their
chasing these animals around the globe, a growing number of scientists are
leveraging the bird's-eye view of orbiting satellites to easily monitor animals'
movements anywhere in the world.
piggybacks on weather satellites called Polar Operational Environmental
Satellites, which are operated by the National Oceanic and Atmospheric
Administration (NOAA), as well as a European satellite called MetOp. Sensors
aboard these satellites pick up signals beamed from portable transmitters on the
Earth's surface, 850 kilometers below. NOAA began the project-called Argos-in
cooperation with NASA and the French space agency (CNES) in 1974. At that time,
scientists placed these transmitters primarily on buoys and balloons to study
the oceans and atmosphere. As electronics shrank and new satellites' sensors
became more sensitive, the transmitters became small and light enough by the
1990s that scientists could mount them safely on animals. Yes, even on birds
like the Oriental Honey Buzzard.
just never had the capability of doing this before," says Christopher
O'Connors, Program Manager for Argos at NOAA.
transmitters weigh as little as 1/20th of a pound and require a fraction of a
watt of power. The satellites can detect these feeble signals in part because
the transmitters broadcast at frequencies between 401 and 403 MHz, a part of the
spectrum reserved for environmental uses. That way there's very little
interference from other sources of radio noise.
being used more and more for animal tracking," O'Connors says. More than
17,000 transmitters are currently being tracked by Argos, and almost 4,000 of
them are on wildlife. "The animal research has been the most interesting
area in terms of innovative science."
researchers in Japan used Argos to track endangered Grey-faced Buzzards and
Oriental Honey Buzzards for thousands of kilometers along the birds' migrations
through Japan and Southeast Asia. Scientists have also mapped the movements of
loggerhead sea turtles off the west coast of Africa. Other studies have
documented migrations of wood storks, Malaysian elephants, porcupine caribou,
right whales, and walruses, to name a few.
Argos data is
available online at www.argos-system.org,
so every evening, scientists can check the whereabouts of all their herds,
schools, and flocks. Kids can learn about some of these endangered species and
play a memory game with them at spaceplace.nasa.gov/en/kids/poes_tracking.
This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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Chairman John Vale-Taylor
Phil Berry 01892 783544
Treasurer Mike Wyles 01892 542863
Publicity & Website Michael Harte 01892 783292Newsletter Editor Geoff Rathbone 01959 524727
Any material for inclusion in the May 2008 Newsletter should be with the Editor by April 28th 2008
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