From: TerryMoselaol.com
Date: Sat, 31 Dec 2005 07:56:21 EST
Subject: HNLS, IAA Party, 2xNM, Aurorae?, Quads, ISS

Hi all,
 
HAPPY NEW LEAP SECOND! The New Year will start at 00h 00m 01s on 1 January,  
on your watch, as an extra second will be inserted after 00.00.00 to  
compensate for the Earth's slowing rotation period! So what makes a body as  massive 
as the Earth slow down? Basically, it's the tides. The gravitational  pull of 
the Moon (ignore the Sun for this purpose) draws the Earth's oceans out  in two 
opposite bulges - one towards the Moon where the pull is strongest, and  one 
on the other side of the Earth, where the Moon's pull is weakest. The Earth  
rotates once per day 'under' those bulges, so they sweep round the Earth,  
causing almost two high tides each day, which pile up against the  Earth's land 
masses as it rotates. The dissipation of this energy  cause the Earth's rotation 
to slow down ever so slightly, hence the extra  second that has to be 
inserted every so often to compensate. 
  As a result of the law of the conservation of angular momentum, that  means 
that the Moon also slowly recedes from the Earth, and so the length of the  
month is increasing by a tiny amount each year also!
 
2. IAA NEW YEAR PARTY - DIRECTIONS:
Here are directions to the Tudor Cinema, Drumhirk Road, Comber, Co  Down, for 
the IAA New Year Party on Saturday 7 January, at 7.30 p.m.:
 
From the Comber by-pass, take the A22 to Killyleagh & Downpatrick. From  the 
roundabout at the by-pass / A22 junction, Drumhirk road is just  under 1 mile, 
on the right. Go up Drumhirk Road for 1/3 mile, and you'll  see some cottages 
on the right, with a laneway opposite, surrounded by  'ranch-style' fencing. 
Go to the end of that laneway, where you'll find the car  park beside the 
cinema. Be there promptly for first choice among the eats and  drinks!
 
3. Two New Moons this month: I didn't mention this before, as it's really a  
'non-event', but as the media & some American sources are hyping it up, I'm  
forced to comment. 
   They're not rare! There are also 2 Full Moons in June 2007,  and 2 New 
Moons in August 2008! In other words, they're far more frequent than  Leap Years! 
And just as predictable.
   (And what about the two Last Quarters in May 2005? Or the two  First 
Quarters in August 2006?) 
   A synodic month (New Moon to New Moon) is 29.53059 days  long, and every 
month except February is longer than that, so they're bound to  recur on a 
regular basis!
 
4. AURORAE: There's a slight chance of auroral activity over the next night  
or two, but don't expect anything too spectacular. 
 
5. METEORS: Look out over the next few nights for the first members of the  
first meteor shower of 2006, the Quadrantids, which peak on January 3d 17h, 
with  a nominal zenithal hourly rate (ZHR) of about 100. Luckily, it's not 
affected by the Moon this  year, so clear skies should reveal a good show of  these 
moderately fast meteors. They are not usually exceptionally bright, so  you'll 
need a good dark site to see them at their best. The radiant is in N  Bootes, 
and is above the NW horizon as darkness falls. It then dips lower, below  the 
Pole, at lower culmination, before starting to rise again in the NE later in  
the evening.
With maximum  forecast for 17h, you should look from the start of 
astronomical twilight on  the 3rd, right through that evening  for as late as you can 
manage, for the best views. Some will also be seen on the  nights of 1/2 and 2/3 
Jan, but the  Quadrantids have a short sharp peak, so not many are seen on the 
nights before  and after maximum. The radiant is at 15h 28m, + 50°, about 
halfway between the  end of the 'Plough' handle and the head of Draco. In a very 
dark sky you might  see about 40-50 per hour early on the evening of the  3rd. 

6. ISS: Another series of evening passes of the ISS starts on 1 January,  
although the best ones don't start until a few days later. Details on 
www.heavens-above.com. 
 
Clear skies to all - especially on 29 March!
 
Happy New Year to all,
 
Terry Moseley
 

Last Revised: 2006 January 3rd WWW contact:webmaster@arm.ac.uk

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