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From: TerryMoselaol.com
Date: Mon, 13 Mar 2006 16:49:52 EST
Subject: PLE, TV, Lectures

Hi all,
 
1. PLE: Just another reminder about the  Penumbral Lunar Eclipse on March 14 
- 15. This will be  barely noticeable to most people, but experienced 
observers may notice that the  Full Moon is not quite as bright as usual, and see a 
slight dimming of the  Moon's SSW edge, the part closest to the umbra, the 
central and  darkest part of the Earth's shadow. The moon passes completely inside 
the  penumbra, or 'partial shadow', of the Earth, but no part of it actually 
enters  the umbra, which would give a partial eclipse. So this is what is 
called a  'Total Penumbral Eclipse' - not to be confused with a Total Lunar 
Eclipse! It  begins on 21h 22m and ends on 02h 14m. The Moon will be just on the 
border  between Leo and Virgo, quite close to Beta Virginis.  
Of academic interest only, I'm afraid, but I attach a map  anyway. If you are 
wondering why the Earth's shadow is not centred on the  ecliptic (the 
diagonal line running from top right to bottom left) on that map,  it's because that 
is the view as seen from Belfast (about 55 degrees  North), rather than the 
'theoretical' geocentric view. That caused some surprise  to a certain 
professional astronomer, but I assure you that it's correct!
   In case you're not sure what's what, the inner dark circle is  the Earth's 
'full' shadow, or umbra: if the whole Moon was inside this, it would  be a 
'total lunar eclipse'. If only part of the Moon was inside it, it would be  a 
'partial lunar eclipse'. The outer lighter ring is the penumbra, or partial  
shadow of the Earth. Since the Moon (yellow disc) is all inside this ring, it's  
a 'penumbral lunar eclipse'. If only part of the Moon was inside that ring, it 
 would be a 'partial penumbral lunar eclipse'.

 
2. TV: Sat, 18 Mar, 12.30pm, BBC2 TV: The Sky at  Night - about Saturn.
 
LECTURES:
3. 20 March, 8 p.m. The Irish Astronomical Society's next talk is   "Worlds 
that Never Were" (Curious Episodes in the History of Astronomy) to be  given by 
the indomitable Mr John Flannery (IAS) on March 20 in Ely House,  Ely Place, 
Dublin.
 
4. 22 March, 7.30 p.m., Lecture Room 5, Stranmillis College,  Belfast: IAA 
Public Lecture, "The Solar Wind: from Explosions on  the Sun to Us",  by the 
redoubtable Dr Miruna Popescu of  Armagh Observatory (Doctorate just awarded - 
congratulations!). I can't resist  quoting most of her synopsis:
   "A few million tonnes of charged particles (plasma) leave  the Sun every 
second.  This continuous stream of electrons, protons and  heavier ions - the 
solar wind - flows into the space between the planets and  even beyond. The 
solar wind flows with a huge speed, equivalent to London  to New York in about 10 
seconds!
Sometimes the solar wind that  reaches the Earth distorts its protective 
magnetic field, producing geomagnetic  storms that can perturb satellites and 
electronic systems, and sometimes create  the most amazing cosmic light displays: 
aurorae -  also known as the  northern lights in our hemisphere. 
How does the  solar wind escape the Sun's huge gravity and leak into  space?
How does it reach such high  speeds?
What are its effects on the Earth's environment?  
How do we know that the solar wind is out there,  constantly surrounding our 
planet?
What are the most up-to-date  discoveries that we have made about the solar 
wind?
These are some of  the questions I am going to answer in my talk.  
   Prepare yourselves to see some of the most amazing images  and movies of 
our Sun, taken with the most accurate solar  instruments.  Fasten your 
seat-belts as you are going to fly around the Sun  with SoHO and TRACE!" (I can't 
wait! TM)
Admission free, and all  are welcome, including light refreshments.
 
5. Messier Marathon: The EAAS will be attempting a  'Messier Marathon', i.e 
trying to observe all the Messier objects between dusk  and dawn, on the night 
of 24/25 March. Obviously that's weather dependant, so  more details later.
 
Clear Skies,
 
Terry Moseley

PLE

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