Now we are spreading out our wings towards space to quiet our curiosities about solar system and galaxy. Since we all belong to planet earth, so we should live like a family of Earth and adopt a common calendar indicating relation of our earth with zodiac. To avoid any discrepancies a new solar calendar is badly needed with the start of 3rd millennium AD This is done by preparing a zodiac-calendar which is scientific and nature based. The calendar is based on revolution of earth around sun passing across different signs in zodiac starting from vernal equinox tropical (sayana) longitudes. The said calendar has synchronization with seasons, solstices and equinoxes along with start and end of a month with respective sign sequentially.

Like the Gregorian solar calendar it is also an arithmetical calendar and counts days as the basic unit of time grouping them into weeks, months and years. with the difference that the calendar repeats completely every 730,485 days of 24 hours each, 104,355 weeks of seven days each, 24,000 months and 2,000 years (having 1515 years of 365 days and 485 leap years of 366 days). Thus completing a cycle of 2,000 years. This gives an average year length of exactly 365.2425 days i.e. 365 days, 5 hours, 49 minutes and 12 seconds. But since the mean tropical year is of 365.242190 days i.e. 365 days, 5 hours, 48 minutes and 45.216 seconds with a difference of 26.784 seconds (0.00031 day) per year i.e. 14 hours, 52 minutes and 48 seconds (0.62 day) per 2,000 years. So we can say difference of 31 days in 1 lakh years. This difference is nullified by creating astronomical days so that the calendar becomes perfect in itself.


Leap days :-

Length of the mean tropical solar year

(equinox to equinox) = 365.242190 days
Here complete solar days in a solar year i.e. 365 will have their own identity and part of a day will have it's own identity. Thus the leap days will have their own identity and will be known as "0" (zero) days so that the no. of days in leap month will remain constant and no change in no. of days in a month having a leap day.

To calculate no. of leap days :-

1 every 4th year
24 every 100 years, and
97 every 400 years.
485 every 2,000 years
484 (if astronomical day 485-1) &
24219 every 100,000 years
(after deduction of astronomical days 24,250 – 31)


alternately :-

No. of leap days in one lakh years :-

@ one leap day in years divided by 4 = 25,000
Less : 3 leap days in century years not divisible by 400 = -750
Less : 31 days in one lakh years as astronomical days = -31
(Leap days omitted of century years divisible by 400)
Total = 24,219 days

To calculate total no. of solar days :-

365 days / solar year + No. of leap days ("0" days) – No. of astronomical days.
e.g. Total no. of solar days in 100,000 solar years will be -
(365 x 100,000) + (97x250) – 31
= 36,500,000 + 24,250 – 31
= 36,524,219 days / lakh years
(N.B. :- 31 is the number of astronomical days in 1 lakh year)
which is equal to the length of 100,000 tropical solar years
365.24219 x 100,000 = 36,524,219 days.

Astronomers day :-

In zodiac calendar there is a provision of updating. In the year divisible by 2,000 the association of astronomers from all around the world will decide the difference of time between beginning of Zodiac-calendar year and tropical vernal equinox (ecleptic longitude) including slowing down of earth's rotation (tidal acceleration and leap second), vernal equinox year (365.24237 days) and changes occurring in time due to nature from time to time. If the time difference is more than 12 hours including all factors. This will be known as astronomical day and the year will not be a leap year (omitting of leap day) i.e. the astronomical day will be subtracted from routine no. of leap days by calculations. The no. of astronomical days will be 31 in a period of 100,000 years with respect to the mean tropical year of 365.24219 days. If required astronomical days may increase or decrease in number accordingly to have synchronization of z-calendar and vernal equinox with difference in hours only possibly less than 12 hours. No. of astronomical day will be one and some times two in a period of 4,000 years.

Beginning of the year :-

First month & first date of zodiac year (Z.Y.) will start when the earth is on vernal equinox, a point of intersection of the ecliptic with celestial equator, so called first point of aries (0^o aries) which is the ascending node of the Sun in relation to the ecliptic on the equator, when it passes from south to the north. The other months will be according to the sequence anticlockwise.

Months :-

Z-calendar is divided into twelve months of irregular length (having equal angular distance of 30^o each in revolving earth path). Duration of month is in accordance to the duration taken by revolving earth across respective sign. According to Kepler's 2nd law of revolutionary planets more time is required for crossing 30^o angular distance when the sun is at aphelion (earth being farthest from sun) and less time required when the sun is at perihelion (earth being nearest to sun). Z-Calendar month time and revolution time across respective sign will differ in hours only (not in days) because a day can not be less than 24 hours duration.

Name of months may be eigher of the following choices.
(a) Digital – starting from 1 to 12
(b) In accordance to capital letter of the English asphabates in sequence starting from A to L.
(c) In accordance to name of tropical signs starting from aries to pisces.
(d) According to the decision taken by international association of astronomers & people of earth.

Table showing beginning of solar months and their duration :-

Week :

Weeks and week days will remain in the same pattern and sequence as they are at present without any change.

Occurance of leap day in a solar year :-

The leap day (intercalary day in a leap year) will take place at the end of 1st month "A" and before the start f 2nd month "B" (when earth has almost crossed sign aries during its revolution) and will be known as "0" (zero) day. Thus not affecting the dates of solstices and equinoxes as well as no. of days in a month. So the first solar month in a leap year will be of 30 days + "0" (zero) day.
Since the revolution time of northern hemisphere is more than 186 days (186.4 days) & of southern hemisphere is less than 179 days (178.8 days) & revolution time across sign aries is nearly 30.45 days, so the leap day will take place at the end of first month only. By doing so, the dates of solstices and equinoxes will remain same every year and not changed due to leap day.

Beginning of Z-Calendar & writing of date, month & year :-

The months are identified by capital letter of English alphabets sequentially starting from A or by number starting at 1. The day of the month numbered sequentially starting at 1.

To avoid any short of complications and to make it easy
Z-calendar can be started from back date i.e. 21st March, 2001 AD of Gregorian Calendar. This date being 1st date of 1st month and 1st year of Zodiac Year (Z.Y.) e.g. 21st March, 2001 AD at 12 hours mid night will be 1st A, 0001 of z-calendar; representing 1st – date of month, A-First month and 0001 start of First year of Zodiac years. The new year to be celebrated at this time every year.

N.B. :- If astronomical day is required at the onset of calendar, zodiac calendar will start from 21st March, 2,000 and astronomical day will take place at the end of first month. This will be known as "0" (Zero) astronomical day and "0" (zero) year. With the view that the Z-Calendar was started on 21st March, 2,000 but practically applied since 21st March 2001 AD. This year will not be counted in zodiac years. This is only to update the time before starting z-calendar. Falling of vernal equinox in a leap year on 21st March between 24.00 hrs. midnight To 6.00 hours morning is preferred.

Table showing beginning dates of solar months, signs and seasons with their duration in days in relation to ecleptic (sayana) longitudes.

Z = zodiac, VE = vernal equinox AE = autumnal equinox
G = Gregorian SS = summer solstice WS = winter solstice
( "0") = occurance of a leap-day
* = tropical astrological zodiac

N.B. :- Solstices and equinoxes are in relation to northern hemisphere of earth. For southern hemisphere they will change accordingly.

4th month "D" (cancer) is a month of aphelion (Earth being fartherest from sun) having 32 days.
10th month "J" (capricornus) is a month of perihelion (Earth being nearest to sun) having 29 days.

Advantages of Zodiac Calendar :-

1. Solar year will start from first point of aries a landmark i.e. vernal equinox (intersection of the ecliptic with celestial equator – a natural phenomena every year).
   
2. Solstices and equinoxes will be always on date 1st of a month e.g. vernal equinox – onset of 1st month. (aries)
   summer solstice – onset of 4th month. (cancer)
   Autumnal equinox – onset of 7th month. (libra)
   Winter solstice – onset of 10th month. (capricorn)
   
3. Seasons (International as well as Indian) will synchronize with start and end of months with respective signs.
   
4. Duration of solar months will synchronize with duration taken by revolving earth across respective signs (difference being only in hours and not in days).
   
5. By representing leap day at the end of 1st month as a "0" (zero) day. no change in no. of days of a month having a leap day because leap days will have their own identity.
   
6. There is provision of updating the calendar, after every 2,000 years. Thus the difference of time between occurrence of vernal equinox and change of Zodiac year will be only in hours (less than a day) for indefinite time even if the changes take place by nature in future.
   
7. The leap day at the end of 1st month is in accordance to Kepler's Law because time taken in northern hemisphere is more than 186 days and in southern hemisphere less than 179 days. Time taken across sign aries is nearly 30.5 days. Hence leap day after every 4th year at the end of 1st month (aries) is quite justified.

Foot Note :

1. ^ This era was created in the 6th century by Roman Monk Dionysius Exiguus.
   
2. ^ Lahiri's Indian ephemeris of planet's position for 2007 AD. page 15
   
3. ^ http://www.washingtonpost.com/wp-srv/artsandliving/horoscopes/index.html
   
4. ^ Sources differ on whether April 20th should be associated with Aries or Taurus.I.e.
   Astrology.com.AU (Taurus) or Astrology online (Aries)

References :

• Retrieved from online
  http://en.wikipedia.org/wiki/gregorian_calendar dt. 29.07.2007
  
• World Book encyclopeda (2001)
  
• Calendar : Humanity's Epic Struggle To Determine A True and Accurate Year, David Ewing Duncan, Harper Perennial, 1999, ISBN 0-380-79324-5.

Dr. M. L. Agrawal