The dates of ancient events and legendary personages greatly agitate people especially if they are concerned with religion and history.
All ancient dates are however very dubious because till fairly recently people had no way to accurately measure the passage of the years. Thus the precise dates of the Mahabharat, Ramayana, Iliad, Buddha, Jesus, Muhammad and others were all very unreliable.
Calculating the passage of time had always been very difficult as the timing of the orbits of the earth around the sun or the moon around earth is most inconvenient. One orbit of the earth around the sun takes precisely 365 days, 5 hours, 48 minutes and 46 seconds while one orbit of the moon needs 27 days, 7 hours, 17 minutes and 28 seconds. People in every land used to carefully observe the moon and had mostly marked their changing seasons according to moon cycles.
People had roughly noted the orbit of the sun to make a year but found it absolutely impossible to divide this by the lunar months because they had no means to divide or multiply until the discovery of the 'Zero', a concept that is attributed to an Indian mathematician named Aryabhatta dated to about 500 AD. In 628 AD another Indian mathematician named Brahmagupta is believed to have developed the symbol for Zero that had been first recorded as a dot under other numbers. This concept of Zero only reached Europe in the 11th century through the Muslim scholar Ibn Sina, known in Europe as Avicenna. He is reported to have learned his mathematics from an Indian grocer in Baghdad.
Till the Zero people could only count with the fingers of their hands and all ancient cultures like those of Egypt, Babylon, Greece, Rome as well as ancient India had therefore been unable to of conceive of time beyond ten thousand years. The complexity of the earth's and moon's orbits resulted in a shifting of all the historic dates with devices like leap years or extra months every four years in some ancient cultures. The methods of measuring time kept changing over the ages.
The seven day week was probably first defined in the old Babylonian calendar where the roughly 28 day lunar month was divided into four. It later became part of the Jewish, Julian, Gregorian and Islamic calendars but had been completely alien to ancient India. With the advent of the Zero, Indian legends suddenly become unbelievably old as more and more zeros were added during each retelling of legendary stories. The dates of the Yugas, Mahabharata, Ramayana and other legends can therefore have very little historic basis.
The old Babylonian calendar used to also have a 60 hour day because the number 60 had been considered to be a sacred number that could be divided by 2, 3 and 5 (the largest number of prime numbers). Ancient Sanskrit texts in India used to also follow this system and measure the day in 60 ghatas (hours) of 24 minutes each. These used to be measured by water clocks where a small earthen pot (ghara) with a small hole that was designed to take exactly 24 minutes to fill up and sink after which a bell (ghanti) would be struck to announce the 'ghanta' or hour. The apparatus was called a 'ghari'. Today, except for Indian astrologers, nobody remembers this old Indian system but it was very precisely detailed in the Persian traveler al -Baruni's chronicle that is dated to 1020 AD at about the time when Mahmud Ghazni was looting Indian temples.
Indian astrology however went beyond the 12 planets of the zodiac and measured the year with 27 (sometimes 28) Nakshatras of 13.5 days each. They were linked not only to constellations but also to many other stars that were believed to have beneficial of malefic influences. This astrological system is not mentioned in the Rig-Veda or early Vedas but only in the Artha-veda that seems to have included a large number of pre- Vedic traditions. All these created a very complicated system of astrology. Though this system has mesmerised the gullible in India over the years, it is clear that none of these scriptures had any scientific basis.
All people are entitled to their beliefs but they should know that many popular beliefs cannot stand the scrutiny of empirical science or unbiased historical research. Even the religious sanctity attached to the days of the seven day week is thus completely alien to ancient Indian texts. If there were no week days there could not have been any auspicious or inauspicious week days as many believe. Thus the sacredness of fasting on Tuesdays or of not buying metals on Saturdays and other similar customs cannot have any scriptural sanctity.