The Science behind the number and order of days of the week

Did you know that the order of weekdays i.e. Sunday, Monday, Tuesday... is defined by India and is used around the world? Read on…

Why are there seven days in a week and not any other random number? Did you have this question when you were a kid?

The order of days in a week are defined according to the speed of the planets/astral bodies with reference to the movement of the Earth. There is a relationship at play. Only those grahas are taken whose vibration/light is within range of affecting the Earth. If we were living in another planet, or another solar system, the number of week days and duration of a day could be so different from what we know of today! This was stated in ancient Indian texts: 7 days in a week (based on the Earth’s relationship with seven neighbours) and that’s how it remains!

Speed of the planets/astral bodies with reference to the movement of the Earth: Moon is fastest, Saturn is the slowest.



  • Sun is the king of the solar system, affects the the first hour (Hora होरा) of the week. It is the lord of the first hour of the week.
  • A day (वार)  starts from sunrise and ends at next sunrise, not midnight.
  • Speed of the seven grahas, with reference to the movement of the Earth is: Moon (being the fastest), Mercury (slower than Moon), Venus, Sun, Mars, Jupiter, Saturn (slowest). This is the order if we place them in descending speed order. But, the Sun being king of the solar system, gets first place and consequently the first hour of the week.
  • The lord of the first hour of the day is the lord of that day too!

Speed order is Saturn (slowest), Jupiter, Mars, Sun, Venus, Mercury, Moon

Sun, the source of light and life is the King of our solar system, gets first hour.   We start the count from the Sun as first, then Venus (next fastest), Mercury, Moon, Saturn, Jupiter and Mars


Weekly Hora- Hours Table (first hour owner graha, owns the day too!)


The 25th hour of Sunday or Ravi-Var is the first hour of the next day. The first 25th hour belongs to Moon (see the above table, 24th hour belongs to Mercury) So by the rule whichever planet gets the first hour, the day belongs to that planet :) So first hour on next day belongs to Moon therefore the day is called Som-Var सोमवार, Monday.

25th hour on Som-Var is of Mars so first hour of the next day belongs to Mars and the day is called Mangala-Var (मंगलवार)

Same calculation continues for the whole week.

Days of the week calculated from the above method-

Sunday- Sun (सूर्य-रविवार), Monday-Moon (चन्द्र-सोमवार), Tuesday-Mars (मंगल-मंगलवार), Wednesday-Mercury (बुध-बुधवार), Thursday-Jupiter (गुरु-गुरुवार), Friday-Venus (शुक्र-शुक्रवार), Saturday-Saturn (शनि-शनिवार)

This word Var (वार) comes from Vasara (वासर). Vas means to stay, Ra means the light of Sun. Where the light of Sun Ra (रा) is staying Vas (वास). So, whichever day of the week it is, the lord of that day will act like the Sun.

The word Hour also probably comes from the word Hora as in Brihat Parashara Hora Shastra :)

This should be taught in schools. How many of us have asked our school teacher, why are the days of the week so? Well, now we know:)

Do share this article with your friends :)

The science behind the week days comes from one of the 6 Vedangas, Jyotish Shastra. Brihat Prarashara Hora Shastra being the most famous explanation thereof. It is in Sanskrit and requires the blessing of a master in the Guru Parampara to reveal the correct interpretation as the Sanskrit language or Dev-bhasha has several layers of meanings and several contexts are attached to each sound, syllable, word, grammar, punctuation and meter. I am a student of Vaidik Jyotish being taught at Ved Vigyan Mahavidypeeth, Bangalore, under the guidance of Gurudev Sri Sri Ravi Shankar ji. Professionally, i make software:)

~ Nitin Sharma


Nitin Sharma
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