Our winter almanac 01.01.2010 – 07.01.2010

In this first post for 2010 we will look at how the Sun and the Winter Solstice set the beginning of the astronomical season of winter and our astronomical time

The beginning of winter and the start of our Astroclock winter almanac 2009-2010 is marked by the coming of the winter solstice. This took place on December 21 2009.

In our part of the world, in what is called the northern hemisphere, the winter solstice is the time when the Sun reaches its southernmost point from the celestial equator. For people living in the southern half of our planet, in places like Australia, Africa and South America, this day of our winter solstice is their summer solstice, because the Sun is shining directly over the southern tropical latitude.

The Earth spins on its axis every 24 hours, giving us our 24 hours and night and day, but this axis has got a tilt of 23.4 degrees. It is this tilt that causes the seasonal changes we see over the 12 months of the year. For instance, on the date of the winter solstice the northern half of our planet is tilted away from the Sun at the full angle of 23.4 degrees, so that sunlight reaching us is not so strong as it is on the summer solstice when our part of the planet is tilted fully towards the Sun.

Over 4,000 years ago, people who lived in our part of southern England used large standing stones to accurately measure out the length of the year from solstice to solstice. The point on the horizon where the rising Sun would appear would be marked using these standing stones. When the Sun rose again at this point 365 days later, these people could tell that a year had passed between the solstices. This was an astronomical measurement. At Stonehenge, not far from Basingstoke, the stones still frame the point on the horizon where the sun sets on the winter solstice.

These days, with our very accurate clocks we can measure the year exactly. For instance, the time between the winter solstice of 1999 and the winter solstice of the year 2000 was 365.24274 days. Even though the ancient people living here 4000 years ago could mark the year, they had no clocks to measure time accurately, or any use for hours, minutes and seconds.

The New Year

In the middle of this second week of our astronomical winter almanac we will celebrate the arrival of a new year.

The year 2010 celebrations mark the time since the year of Christ’s birth, even though many people think Christ was born 2006 years ago in the reign of King Herod.

The calendar that makes this year the year 2010 was devised many centuries ago by a man called Dionysius Exiguus, which means ‘Little Dennis’. He was a brilliant scholar, mathematician and astronomer. In the year 525AD, Pope John I asked Dionysius to calculate the date for Easter for the following year 526AD.

When he had completed his work calculating the date of Easter for the next 95 years Dionysius also invented a system of dating known as anno Domini, or AD. This is the latin for ‘the year of our Lord’.

In the year we now call 531 AD, when Dionysius created this system, the number of the year was 247 anno Diocletiani, the year of the Roman Emperor Diocletian, a notorious persecutor of Christians. So Dionysius counted back the years to the year he believed Christ was born, and gave this year the number 1, preferring a Christian beginning to the numbers of the years.

Beginning with One or Zero

Dionysius wasn’t able to make the year of Christ’s birth AD 0, because the idea and symbol for zero had not yet been introduced into the European lands. So, some people say that because Dionysius began his calendar with the year 1, all the special celebrations during the so called millennium year of 2000 were in fact happening in the last year of the twentieth century and the very last year of the second millennium.

Christmas in January!!!!!
Wednesday 6th January is a Christmas Day (Armenian Orthodox)!
Armenian Christians celebrate Christ’s birth at Epiphany, except for Armenians in the Holy Land, who celebrate Christmas on January 19th. Theophany (Orthodox), Orthodox churches mark the baptism of Jesus on this day. Epiphany celebrates the visit of the wise men (the magi) to the infant Jesus. In the East, where it originated, the Epiphany celebrates the baptism of Jesus by John the Baptist in the River Jordan. (Catholics and Episcopalians celebrate this separately: see Baptism of the Lord) Also known as Dia de los Reyes (Three Kings Day).

Thursday 7th January is Christmas Day for Orthodox Christians. Most Orthodox churches use the Julian rather than the Gregorian version of the Western calendar(more about this in future posts and pages). As a result, they celebrate Christmas 13 days later than other Christian churches.

Fairfields School 07.01.2010

From the Winter Solstice the days get longer but the weather gets colder and more wintry over the next couple of months. This is because the rate of heating of our part of the planet’s atmosphere from the Sun’s rays is offset by the rate of cooling and the reflection of heat from the planet’s surface.

Photo of a part of the sky during a meteor shower over an extended exposure time. The meteors have actually occurred several seconds to several minutes apart.

Shooting stars

The first meteor shower of the year takes place this week between January 1 – 4. The best show of these shooting stars will be on the January 3. Look out for them in the area of the night sky where you can see Bootes the Herdsman. These meteors are called the Quadrantids because they appear in the part of the night sky where a rather faint constellation looks a bit like a navigators quadrant.

Boötes the Herdsman was the Fairfields School Astroclock Logo. Exactly whom Boötes is supposed to represent is not clear. According to one version, he was a ploughman who drove the oxen in the constellation Ursa Major using his two dogs Chara and Asterion (from the constellation Canes Venatici). The oxen were tied to the polar axis and so the action of Boötes kept the heavens in constant rotation.

Finding your way around the night sky

A planisphere is very useful in finding your way around the stars and constellations of the night sky. A planisphere is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist in learning how to recognize stars and constellations.


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