SCIENTIFIC CORRESPONDENCE


CURRENT SCIENCE, VOL. 84, NO. 1, 10 JANUARY 2003 21

Possible errors in historical dates: Error in correction from Julian to
Gregorian calendars We have studied five major historical events reported
between 1630 and 1680 AD, where detailed references to the stars in the night
sky are available. We show that the descriptions of the star patterns at that
time are off by exactly ten days.



For example, the solar eclipse reported in one example to occur on 20 March 1680
in fact occurred on 30 March 1680 according to the current (Gregorian) calendar.
This is checked using a computer simulation package (SkyMap Pro) and Oppelzer's
Canon of Eclipses1. We attribute this error in dating historical event(s) due to
the switchover from Julian to Gregorian calendars in the latter half of the 18th
century. Important events in Indian history are dated to an accuracy of a
specific date that is calculated based on the documentation of a specific
period(s) and historical references. However, it is often difficult to verify
these dates by independent means since historical references do not often carry
independent markers. However, documents on comparatively recent Indian history
often give detailed description of astronomical events, which can be
independently verified using modern software programs designed using data from
high precision astrometry satellites like Hipparcos and Tycho. It is observed
that while writing the history of Shivaji Maharaj, nearly all the evidences are
written according to the Julian calendar. Due to many defects, this calendar was
reformed by Pope Gregory in 1582 AD and it was announced that after 4 October
the next date will not be 5 October but 15 October.



Hence ten days were deleted from the Julian calendar, which is now named as the
Gregorian calendar. The Catholic community immediately accepted this change but
the Protestants, including the British accepted it only after 170 years, that is
on 2 September 1752 AD. They took the next day as 14 September 1752 AD. This has
a difference of 11 days because in the 170 years the difference between the two
calendars increased from 10 days to 11 days. As the Protestants were ruling many
countries across the world, such countries continued to use the Julian calendar
till that time. In India also all the history written by British historians is
according to the Julian calendar up to 1752 AD. Julius Caesar introduced the
Julian calendar and put it in practice in 45 BC.





The duration of a year in his calendar was 365.25 days as found by the
Egyptians. It differs from both the sidereal period Nakshatra varsha of 365.2564
days used in India and the tropical year of seasons equal to 365.2422 days. The
two differ because Vernal Equinox (ascending node of earth's orbit) moves
backwards, that is towards the west due to the precession of the earth's axis of
rotation around ecliptic poles at the rate of about 1 degree in 72 years. This
produces a difference of 1 day in about 71 years in the Indian calendar, and of
1 day in 128 years in the Julian calendar. In 325 AD, the sun used to enter
Vernal Equinox on 21 March. In the Julian calendar therefore, it was declared
that 21 March will be the Vernal Equinox day and it was related to the
resurrection of Christ. However, the error due to precession was not taken into
account while fixing this date. By the late 1500s the discrepancy became marked.
In 1582 AD, i.e. in 1258 years, the sun started entering the Vernal Equinox ten
days earlier (1258 × 0.0078 = 9.8 days). So on 11 March the sun entered the
Vernal Equinox point. To correct this problem, Pope Gregory cancelled ten days
of that year and after 4 October 1582 the next day was declared as 15 October
1582. The period of Gregorian calendar is 365.2425 days. So, there is still a
difference of 0.0003 days. In spite of this, for the next 3000 years the sun
will enter Vernal Equinox near 21 March2. In the history of Shivaji Maharaj,
historians have converted the moon's position (Tithi) into Julian dates.
However, after the British left, India has continued to use the Gregorian
calendar introduced by the British in 1752. So, from 1582 to 1752 AD the
difference of 10 or 11 days is also reflected in the calculation of Tithi. As a
result, by Julian calendar 20 March 1680 was new moon, but by Gregorian calendar
it was on 30 March 1680. This is highlighted in the records of events associated
with the life and times of Shivaji Maharaj. A difference of ten days is also
noted in the eclipse of January 1665 and August 1673, in the dates of stone
inscriptions of Karnataka3.



According to historians4, the date of birth of Shivaji Maharaj was in the month
of Falgun and the Tithi was Vadya Tritiya. Bhavar, Baneda and Bikaner horoscopes
of Shivaji Maharaj indicate that he was born on Sinha Lagna5. Time of birth
mentioned in Jedhe Shakavali and Shivabharata volumes yields Simha lagna only.
This is three days after the full moon day of the month of Falgun.



This also means that the moon was near the asterism Purva or Uttara Falguni (in
Leo) when it was full and after three days, it was in Hasta (Corvus) or Chitra
(Spica) in Virgo asterism. Also, three days after the full moon day, the moon
must have risen 156 min (52 × 3) later than on full moon night. So the moonrise
must be approximately at 9 p.m. At that time the rising zodiacal constellation
was Virgo. But the birth time of Shivaji Maharaj was in the evening, after
sunset. So at that time the earlier constellation

Leo must be rising on the eastern horizon.





In the history of Shivaji Maharaj, his birthday is mentioned as 19 February
1630. However, the above references do not match with the star patterns on this
date as extrapolated back in the Gregorian calendar. They match very precisely
on 1 March 1630 (ten days later). Another and probably more accurate example is
the partial solar eclipse visible from fort Raigad in the year 1680. In the
various biographies of Shivaji Maharaj, it is mentioned that partial solar
eclipse was visible on 20 March 1680.



From the Gregorian calendar there were no chances of an eclipse on that day
because the sun was in Pisces and moon was in Libra. But on 30 March 1680, an
eclipse did occur. It was in the constellation of Pisces. From Raigad the
eclipse started at 4 h 37 min in the evening. The sun was 30 degrees above the
horizon. The mid-eclipse time was 5 h 41 min in the evening. The sun was only 15
degrees above the horizon. The eclipse ended at time 6 h 38 m in the evening
when the sun was only 1.5 degrees above horizon1. This observation exactly
matches with the documented history. Table 1 gives many other events in the life
of Shivaji Maharaj, which confirm our observations. All the tithis are taken
from ref. 4.















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