Thousands of years ago, ancient Greek astronomers calculated that the track of the Earth’s axis is constantly, even if in a very slow way, shifting in a uniform pattern. The variation is very similar to the manner a spinning top slowly leans one way and then another as it slows down. It is a wobble that happens as its axis alters direction.
This odd movement of the planet is due to several factors, the most important of which is something called ‘precession’. Precession stems from the fact that the Earth is not a perfect sphere. It is in fact about twenty-seven miles longer around the Equator that it is around the Poles. The Earth then is oblate, or fat around the middle like middle-aged spread, but it is due to the spinning not to its age.
If you picture the Earth with its Poles off centre. Then rotate that image and you will find that any point, except the very centre of the axis, will travel in a circle. But very, very gradually. So slowly that it takes 26,000 years to go full circle and get back to where it started from.
This point then, any point you want, is very gradually shifting its position in relation to the stars because the axis is rotating too. The result of this is that, what we call the North Star (formally known as Polaris, which is actually one degree off true North) will not be above our North Pole one day. In fact, by about 15,000 AD, Vega will be almost above the North Pole, although it will be about four degrees off true North. But even this will not last, and by 28,000 AD, Polaris will be back above where it is nowadays.
One of the effects of the precession is that seasons change. They modify the dates that they take place, so that Summer could come earlier or later. The amazing thing about our calendar is that it is corrected for that (with the leap year). If it were not, the vernal or Spring equinox would move over 13,000 years from March 21st to September 21st., which is the date of the autumnal equinox, precisely half a year later.
It is for this reason that the precession of the Earth is generally referred to as the “Precession of the Equinoxes”. Although the precession of the equinoxes is very lengthy, it can be readily observed. The correct year of 325.25 days is the length of time from one vernal equinox to the next vernal equinox, however, it takes 20 minutes and 24 seconds longer for the Sun to appear in exactly the same place in relation to the stars behind it over the same period, which is why accurate star maps have to be stamped with the exact time and date to which they relate.
Owen Jones, the writer of this article, writes on many subjects, but is currently involved with researching Franklin planner pages. If you have an interest in calendars, organizers or promotional calendars, please go over to our website now at Promotional Desk Calendars
The Ancient Chinese Lunar Calendar
Wednesday, February 17th, 2010Prior to their adoption of the Western solar calendar scheme, the Chinese almost wholly followed their own lunar calendar for determining the times of planting and harvesting and festival days. Although people in China today use the Western calendar for almost all business, governmental and practical matters of daily life, the old method still serves as the basis for determining many seasonal holidays. This coexistence of two calendar schemes has long been accepted by the people of China.
However, this does not only happen in China, it also happens in most other Eastern countries, like Thailand, and most Arabic countries.
A lunar month is determined by measuring the period of time needed for the moon to complete its full cycle of 29 and a half days, a standard that makes the lunar year a whole eleven days shorter than its solar counterpart. This difference is made up every 19 years by the addition of seven lunar months.
The 12 lunar months are further divided into 24 solar divisions characterized by the four seasons and times of heat and cold, all of which bear a close relationship to the annual cycle of agricultural work.
The Chinese calendar - very much like the Hebrew calendar- is a combination of the solar and lunar calendars in that it strives to have its years concur with the tropical year and its months coincide with the synodic months. It is not surprising that a few similarities exist between the Chinese and the Hebrew calendar.
For instance, an ordinary year has 12 months, a leap year has 13 months. An ordinary year has 353, 354, or 355 days, a leap year has 383, 384, or 385 days. When determining what a Chinese year will be like, one needs to make a couple of astronomical calculations.
First of all, you have to work out the dates for the new moons. In these instances, a new Moon is the completely black Moon (that is to say, when the Moon is in conjunction with the Sun), not the first visible crescent, as is used by the Islamic and Hebrew calendars. The date of a new moon is then the first day of a new month.
The reason why the majority of countries which had their own calendars had to dump them in favour of the Western, Julian calendar that we use today, is business. First the British and then the Americans ran international business and they used the Gregorian calendar. Anyone who sought to work with them had to follow suit. This is why national policy often varies from local custom in Third World countries.
The government desires to trade on the International markets, but the ordinary family in the country can not. So, the government adopted the Gregorian calendar but the people only pay lip service to it. I live in Thailand and people here do not even use the 24 hour day divided into two halves. Their day has four sections of six hours each and the first part starts at 6AM, not midnight. Therefore, they have four 4 o’clocks a day, for example but no 7 o’clocks. They are also 543 years ahead of us, although this is more common, for instance in Muslim countries.
Owen Jones, the writer of this article, writes on many subjects, but is currently involved with researching Franklin planner pages. If you have an interest in calendars, organizers or promotional calendars, please go over to our web site now at Promotional Desk Calendars
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