The most distinguished feature of the astrology in India or HINDU astrology is the fixed type calendar.
The actual position of constellation in the sky moves slightly in fifty seconds per year against the daily calendar
of Sun type established.
This shift will become some thirty degrees in 2150 years accumulated.
We see the moving position of the equinox along the ecliptics observed either in the constellation Leo in some
ten thousand years ago or in the constellation Pisces in 2000 AD found.
We call this type of moving
point of equinox to be the
TROPICAL type system established. The most people in nowadays world have accepted
the
TROPICAL type calendar for the astrological prediction performed.
On the contrary to the
TROPICAL system,
the system of fixed type equinox is called as the
SIDEREAL type system.
The
SIDEREAL system calendars
have been accepted by the most fortune tellers in India as well as those of either in China or Japan of Oriental
system of fortune telling arts performed.
We can use the same system of observation of the sky either in the astronomy or the astrology for the ancient through
the long future period continued as we employ the tropical system of moving equinox established.
It is entirely different in the sidereal system of fixed equinox that we must have new calendar for fortune tellers in
once for hundred years elapsed.
The stars in the sky will move one degree or more per one hundred years elapsed. For those countries such as either India or Arab countries or China or Japan where the
fortune tellers are using fixed equinox calendars, the periodic modification on the art of fortune telling system will be inevitable.
Indian government has been issuing a proper calendar for the sidereal system frequently to meet the changing point of
equinox authorized. In other countries where the fixed system of equinox has been employed, the minor modification of
the art of fortune telling system has been released under the name of improved art. Thus the pretended authorized system
has been modified to meet new equinox without telling the change officially announced. It is however impossible for the
western type astrology to alter the system easily that so many literatures have been released since the Grecian era. Easy
modification in the Oriental systems can be made easily as only few books were released in the old ages.
ずれています。約二千百五十年経過すると、星座の位置は
三十度ずれます。 この状態を太陽の通り道の黄道（こうどう、エクリプティク）で表示すると、約一万年
まえに獅子座に存在した３月20日の春分点が紀元2000年には魚座の終わりに移動します。