AMATEUR ASTRONOMY:

LUNAR ECLIPSE NOT VISIBLE IN MANITOBA:

As with so many other astronomical events the first total lunar eclipse to coincide with the winter solstice since 1638 isn't visible tonight in Winnipeg as yet more snow drifts gently down to move us to the wettest year in history. Here in the Central Time Zone the umbral phase is due to begin at 12:32 am, and totality at 1:40 am. Totality will last until 2:53 am, making this one of the longer eclipses. There are two lunar eclipses due next year, so better luck next time.

For the curious you can read all about this eclipse in a wikipedia article now on the web. The full eclipse will be basically a North American event this time around with the old world and much of South America missing large parts of the event. For places other than here in the Great Canadian Snowdrift the wikipedia article gives a chart of the phases for various time zones. A good source for viewing conditions in your locale is the Clear Dark Sky website. Much better and more detailed than the average weather report. For those diehards who just have to see something NASA will host a webcam real time version of the eclipse here. Seems like a very poor substitute to me, but to each their own. There will also be a chat room at the NASA site so you can either praise or howl about viewing conditions where you live.

All I can say is better luck next year.

LUNAR ECLIPSE FACTOIDS:

As a supplement to what I have already said about the upcoming lunar eclipse here are a few "factoids" that you may find of interest. First of all, the Wikipedia online encylopedia has an interesting article on this matter, but an much better source is the NASA Eclipse Home Page. It gives just as clear an explanation as the Wikipedia site and has links to many other things that the Wikipedia site lacks.

There is, by the way, a scale for the degree of "luminosity blocking' of lunar eclipses, devised by the French astronomer Andre Danjon. It is as follows:

L=0 Very dark eclipse. Moon almost invisible, especially in mid-totality.

L= 1 Dark eclipse. Gray or brown colour. Features of the Moon only distinguishable with difficulty.

L=2 Deep red or rust coloured eclipse with a very dark central part and the outer edge of the umbra relatively bright.

L=3 Brick red eclipse, usually with a bright or yellow rim.

L=4 Very bright copper red or orange eclipse with a very bright blueish rim.

It'll be interesting to see what tomorrow's eclipse turns out like. Most of the lunar eclipses that Molly has viewed have been in the L2 or l3 categories above.

Here's a brief list of some of the notable lunar eclipses in history and the events they have been associated with.

a)Oct 9th, 425 BCE, choice of Cleon in Athens

b)August 28th, 413 BCE, siege of Syracuse

c)April 15th, 406 BCE, fire in the temple of Athena in Athens

d)Sept 20th, 331 BCE, eclipse before the battle of Arbela of Alexander the Great

e)March 23rd BCE, death of Herod (note the problem with dating the birth of Christ!)

f)Sept 14th, 14 CE, death of Emperor Augustus

g)April 3rd, 33 CE, presumed death of Christ (the possible dates reported in the Bible accord with no reported solar eclipse)

h)May 22nd, 1453, fall of Constantinople

i)March 1st, 1504, eclipse reported by Columbus

j)July 31st,1776/Jan 23rd, 1777/July20th,1777/Dec 4th, 1778: eclipses reported by captain James Cook

k)Jan 15th, 1805 Lewis and Clark eclipse

l)July 4th, 1917 Lawrence of Arabia's eclipse

As a final factoid lunar eclipses are predictable because of a phenomenon known as the 'Saros cycle'. This means that these eclipses will reoccur in about 18 years, 11 days and 8 hours. This periodicity occurs because of the concurrence of three different cycles in the Moon's position vis-vis both the Sun and the Earth. The first is the "synodic period", about 29.53 days, the usual period of the Moon's revolution about the Earth. The Moon, however, makes a revolution about the Earth at an inclination of about 5 degrees relative to the Earth's path about the Sun-the ecliptic. twice during a period of 27.21 days the Moon passes through this plane where an eclipse can occur. This is known as the "draconic month". Finally, the Moon orbits the Earth at a variable distance, varying from apogee (its furthest point) and perigee its closest point in a period of 27.55 days known as the "anomalistic month". The coincidence of these three periods occurs about every 18 years and hence the recurrence of the lunar eclipses. The complication is that each turn of the Saros cycle results in a time difference of about 8 hours vis-a-vis any point of Earth. To learn more about this go to either the Wikipedia article or the NASA article on same.

Molly