Eclipse, Decadal change, NY Party, Perihelion, Quadrantids, Next IAA lecture‏

Hi all,

1. PARTIAL LUNAR ECLIPSE, New Year's Eve: The last day of the Noughties (but see below) will be marked by a partial eclipse of the Moon. But don't get too excited, as it's only a small partial, with a mere 8.2% of the Southern edge of the Moon entering into the Northern edge of the Earth's main shadow, or Umbra.
The barely noticeable penumbral phase will start at 17.15, and the umbral phase begins at 18.52. Maximum eclipse occurs 19h 22m 41s. The umbral phase ends at 19.53, and the Moon will leave the penumbra at 21.30. The 'penumbra' is the Earth's outer, partial, shadow, caused by the fact that the Sun is a disc, not a point source of light.
The Moon will have almost exactly the same apparent diameter as the width of the ring of the Earth's penumbral shadow, so the umbral phase will begin just as the entire moon enters the penumbra.
The Moon will be in Gemini, just S of 3rd mag Epsilon Gem.
N.B. In spite of what you might have read in an email from another source, the shadowed portion of the Moon will not appear "black", let alone "absolutely black"!
In fact, even during mid eclipse, the shadowed portion of the Moon will not appear very dark at all - it is most likely to be a reddish or orangey grey. This is because the Earth's atmosphere refracts or bends an appreciable amount of sunlight onto the eclipsed portion of the Moon. In fact, even during the very deepest and longest of Total Lunar Eclipses, the Moon does not disappear completely, because of this refraction effect.
You can watch out for this at the next Total Lunar Eclipse visible from here, which will mark the next winter solstice: 21 December 2012!
And BTW, please help to counter the false idea circulating that this will be a 'Blue Moon' because it's the second Full Moon in a month! That erroneous description started when Sky & Telescope wrongly interpreted an old New England Farmer's Almanac as calling the 2nd FM in a month a 'Blue Moon'. They later admitted that they had got it wrong, and published a correction, but not everyone saw the retraction. A 'Blue Moon' means a very rare and unpredictable event, and it arose after the great Krakatoa eruption in 1883 blew so much fine volcanic ash into the upper atmosphere that for a while the moon did sometimes appear blue. But that was almost a one-off, and so the term means 'hardly ever'. Whereas there are actually two full moons in the same month every few years or so!

2. END OF DECADE; NAME FOR NEW DECADE. When I referred in my last email (and above) to the eclipse on New Year's Eve being on the last day of the 'Noughties', I wasn't being strictly correct. At least not if one takes the correct definition of a decade, as Brian Beesley reminded me.
Déjà vu all over again! As I pointed out ad nauseum at the time, but to no avail, the last millennium did not end on 31 December 1999, but on 31 December 2000. But I, and Brian, and a few other purists, were 'lone voices crying in the wilderness', so I more or less gave up, and gave in to all the hype, and celebrated the end of 1999 and start of 2000 along with everyone else.
So if one counts that as the start of the current decade, as almost everyone did even if incorrectly, then the end of this year will be the end of that 10 year period, or decade. But strictly speaking, counting from year 1 CE, the current decade does indeed last until 31/12/2010.
But anyway, I was referring to 'The Noughties', i.e. the years which can be said as 'Two Nought Nought Nought' through to 'Two Nought Nought Nine'. (I claim to have been the first to have suggested that term, back in 1996, and no-one has ever told me otherwise!)
So as next year will not be a 'Noughtie', what will we call the next decade? I suggested 'The Teenies', since most of the years will end in 'teen, e.g. Two Thousand and Thirteen etc. But that term does not encompass 2010, 2011, or 2012, because of the vagaries of our enumeration terminology! So I asked for alternatives for this period.
Seamus Bonner suggested 'The Tenners' for the whole period, which is very good for the first year, but only by extension can it cover the rest of the period.
Alan Watson suggested that while the Teenies is OK for the rest of the period, we simply call the next 3 years 'the Pre-Teens'. Simple, apt and accurate. But the "Pre-Teenies" doesn't roll off the tongue so easily as the best suggestion I've had yet -
It's from Donald Ferguson, who suggests the "Tweenies" (in between the Noughties and the Teenies)

So unless anyone comes up with a better idea, I'll go for The 'Tweenies' followed by the 'Teenies' from 2013. You read it here first!

3. IAA NEW YEAR PARTY: Don't forget: The Galaxy's social event of the year will take place on Saturday 2 January, with the highlight being the special private showing of "Star Trek 2009" in the Tudor Private Cinema, Comber.
Thanks once again to George Brannan, for making all the arrangements.
We will meet first for eats in McBrides, in The Square, Comber, at 5.30 (to be ready to eat at 6 p.m.), then move on to the Tudor Cinema, Drumhirk Road, just outside Comber on the A22 Comber to Killyleagh Road, at 7.30 p.m. More details of venues with full directions later.
The programme includes the meal at McBrides, plus the film, plus at the cinema you can warm up with my famous hot punch and mulled wine, reputedly the best in this arm of the galaxy. Soft drinks + tea & coffee also available, all included in the price!
The film will be followed by George's diabolical quiz (and then there's his singing in the musical round too.....), with the usual amazing selection of prizes for almost everybody! The quiz is free to enter too!
Bookings have now closed, so if you haven't already done so, you'll have to wait until 2011.

4. PERIHELION: The Earth will be at its closest point to the Sun on 3 January, at 00.09, at a distance of 147,086,033km, or 0.9832904 AU. Here in Ireland we'll be a bit further away, which must explain why it's so flippin cold!
OK, just in case any of you don't realise that I'm joking - our Northern winter is entirely due to the seasonal tilt of the Earth's axis, and nothing to do with the fairly slight changes in our distance from the Sun, from perihelion to aphelion!

5. QUADRANTIDS. The first meteor shower of 2010 is the Quadrantids, which peak at 18h on 3 January. This shower is brief, but intense, with a maximum ZHR of around 80. The ZHR, or Zenithal Hourly Rate, is the number of meteors which would be seen by an experienced observer, with the radiant in the zenith, in a perfectly clear very dark sky. In practice, observed rates are usually a good bit less than this. This year, the main problem will be an 18day old waning gibbous Moon, which will rise about 20.30. Nevertheless, it will be worth having a look, especially in the few hours between onset of darkness and moonrise. Some Quadrantids can be seen from about Jan 2 through to Jan 4-5.
The radiant lies roughly halfway between the end of the handle of the Plough, and the head of Draco, or just above a point 2/3 of the way from Vega to the end of the Plough handle.
The radiant is circumpolar from Ireland, so it never sets, and as darkness falls it will be lowish in the NNW, then it sinks a bit lower as it passes beneath the Pole, before starting to rise again in the NE.
The further North you are, the better, as the radiant will be higher in the sky at any given time during the night.

6. NEXT IAA LECTURE, 13 January: The first of the Irish Astronomical Association's public lectures of 2010 will be given by Dr Jorick Vink, of Armagh Observatory.
His talk is entitled "The Most Massive Stars in The Universe", and promises to be a fascinating subject. After all, the Sun is 328,935 times more massive than the Earth, and yet we know that there are stars maybe 50-60 times more massive than the Sun. But are there even more massive ones? And is there an upper limit? And how to these stellar heavyweights live their lives? Their lives seem to be relatively brief, but very spectacular!
It's on WEDNESDAY 13 JANUARY, at 7.30 p.m., in the Bell Lecture Theatre, Physics Building, Queen's University, Belfast. ADMISSION IS FREE, as always, and includes light refreshments. Everyone is welcome! Full details of the rest of the programme are on the website: www.irishastro.org

Finally, HAPPY NEW YEAR TO YOU ALL, and welcome to the 'Tweenies'.

NB: If you wish to have your name removed from this mailing list, please just email me back saying so.

Clear skies,

Terry Moseley