Kalacakra Calendar

The Kalacakra Calendar.


A key component of the Kalacakra system is the calendar described in the first chapter of the Kalacakra Tantra. Here we publish several versions of the calendar, calculated for different major world cities.

Below there follows an introduction to the calendar.

Description - click here for a general description of the calendar.
Calendar description - click here for a description of the calendar published here.
Symbolic details - click here for some details about the information in the calendar.
Choose calendar - click here to view the list of calendars available.
Astrology associated with Kalacakra - click here for notes on the astrology associated with the Kalacakra calendar.
Download calendar software - click here for downloadable software to create the Kalacakra calendar.

Traditional Tibetan calendar archive - click here to access an archive of traditional Tibetan calendars.
A Reformed Tibetan Calendar - details of a recent attempt to reform the Tibetan calendar.



Introduction.

One of the main topics to be discussed in the first chapter of the Kalacakra Tantra is the creation of a calendar. There are many misconceptions regarding this system. The Tibetans used it as the basis for their calendar (see Svante Janson for an extensive description of this), which theoretically started in 1027, but have mostly never followed the precise instructions as given in the original Kalacakra literature. There are therefore strong reasons for saying that the Tibetan calendar is in need of reform.

So, the calendar presented here is not a Tibetan calendar as can be purchased nowadays in Lhasa or Kathmandu, but is based as closely as possible on the instructions given in the Kalacakra literature, with the exception, of course, that we need not use all of their methods, and can instead use modern technology where appropriate.

However, there is one calendar that was developed in Tibet in the 15th century in the system known as the "Correction of Error" ('khrul sel) that closely followed the instructions in the original Kalacakra literature. If that calendar had been developed further and then maintained by means of regular adjustment on the basis of observation, it would be essentially the same as the calendar presented here. More about this in the description of the calendar. Another misconception - very common in the west - is that the Tibetan, and therefore the Kalacakra, calendar is based on a sidereal, rather than a tropical zodiac. Exactly the reverse is the case.

The difference between these two zodiacs is as follows. In both cases, the zodiac is a division of the ecliptic into twelve equal parts called signs, or zodiac signs. These are therefore all 30 degrees in size. The ecliptic is the path the Sun follows through the sky during the year, and the position of the Sun, and also of the Moon or planets, at any one time is given as a measure of angular distance from a starting point in the ecliptic. This distance is called longitude.

The zodiac begins with the sign of Aries, and the point right at the beginning of Aries is called the first point of Aries. In the west, longitude is measured in terms of degrees, or of a combination of signs and degrees. So, if the Sun is said to be at a point 10 degrees within the sign of Gemini, as Gemini is the third zodiac sign, the Sun is therefore 70 degrees from the first point of Aries.

The difference between the two types of zodiac lies in the definition of the position of the first point of Aries. In the tropical zodiac, the first point of Aries is defined as the position of the Sun at the vernal equinox - at this point the plane of the Earth's equator and the ecliptic cross, and when the Sun is in that position in the Spring, day and night are of equal length. The tropical zodiac is the one most commonly in use.

Due to the phenomenon known as the precession of the equinoxes, the tropical first point of Aries is slowly moving against the background of the stars - the movement is at a rate of approximately 50 seconds of arc each year.

In a sidereal zodiac, the first point of Aries does not move relative to the stars, but is a point within the fixed stars. It's position varies with different traditions, but it is in the region bordering the constellations of Pisces and Aries. The uncertainty regarding the definition of the sidereal first point of Aries is not the only problem with a sidereal zodiac. Due to precession, the ecliptic moves relative to the stars, and away from this point in the stars. So, if the sidereal first point of Aries is defined for some hundreds of years ago, the Sun no longer actually crosses that same point, and as the years pass, is moving further away from it each time it passes by.

Approximately 1,500 years ago, these two zodiacs coincided, but due to the precession of the equinoxes, the tropical first point of Aries is slowly moving against the fixed stars, and has by now drifted to a point approximately on the border between the constellations of Aquarius and Pisces.

New Year in the Kalacakra calendar takes place in spring, and as the system is based on a tropical zodiac, it will always occur in spring. However, if the calendar were instead based on a sidereal zodiac, New Year would slowly drift later through the seasons.

It is surprising that so many westerners believe the Kalacakra and Tibetan calendars to be based on a sidereal zodiac, because the Kalacakra Tantra commentary, the Vimalaprabha, leaves no room for any such view, and makes the point very strongly.

Most Indian systems of astrology and calendars are in fact based on sidereal zodiacs, and the Vimalaprabha explicitly criticises such systems for not understanding the true position of the Sun. It describes how the calendar needs to be adjusted regularly by means of direct observation in order to correct the solar position.

It states that without a correct value for the longitude of the Sun, then the longitude of the moon will be wrong, and so will those of the other planets. With all these wrong, any prognostications made will also be wrong. It states that such methods are meaningless.

The observation that it says is needed is to time the occurrence of the winter solstice, by means of measuring the longest midday shadow of the Sun. Once that has been determined, then the Sun's longitude has to be corrected for that time to equal zero degrees Capricorn. Zero degrees Capricorn is the exact position of the Sun at winter solstice in a tropical zodiac, and the Vimalaprabha calls this the primary definition (muladhruvaka) for it's calendar. The point could hardly be made more clearly.

(The Vimalaprabha actually gives the corrected longitude as 20;15,0, which is a measurement in a system that divides the zodiac into 27 equal bands, each of which are further subdivided into 60 parts. A simple calculation will show that this equals zero degrees Capricorn.)

The methods used by most Indian systems rely on complex calculation systems that were described in textbooks (siddhanta), and expected to be accurate over long periods of time. Clearly, the Kalacakra system is opposed to this method, because over long periods of time small errors will accumulate and become significant. The methods described by the Kalacakra system would have seemed quite radical in 10th century India, and looked at in this way, the Kalacakra system has quite a reforming spirit to it.

Perhaps these issues were not well understood in Tibet. As most Tibetans have not adjusted their calendars according to the methods described in the Kalacakra literature, their main calendar now uses a position of the Sun which differs from that in a tropical zodiac by about 35 degrees - more than a whole sign of the zodiac. Their solar position is also not consistent with a sidereal zodiac, and is simply wrong - it is not a matter of sidereal or tropical. The intention was to base it on the Kalacakra system, but the methods needed were either not understood or were for some reason rejected.

The irony of course is that the Tibetans, who have otherwise preserved the Kalacakra system so well, when deriving their calendars have fallen victim to just those errors that the Kalacakra so strongly criticises.

E. Henning.

 Last updated 1st January 2008.

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