How names of days of week were formed

Planetary Hours / Hora:
Vedic day is a period of 24 hours starting from the sunrise to the next sunrise.This period is split into two periods, daytime and night time. The time period from Sunrise to sunset is considered daytime and from Sunset to sunrise of the next day is night time. Then these two periods are each divided into twelve equal length hours, which are the planetary hours or Hora as we call it in Vedic astrology. The planetary hours of the day and the planetary hours of the night will be of different lengths except on the Equinoxes, when light (day) and darkness (night) are balanced.

Planetary Hora or Hora is one of the most important part of Muhurta and the basis for determining the order of the weekdays.

Hora is derived from Sanskrit word hora (होरा) and is usually called as Hour.

People think that Hora is a Greek word, but Varahamihira clarified that it was derived from Ahoratra.

‘AHO-RATRA’, which means day and night taken together. Omitting the first letter ‘A’ and the last three letters ‘‘TRA’’, the word ‘HORA’ is coined from which, the English word ‘HOUR’ originated.

There are 24 HORAS in all. The division of 12 signs into 24 horas is based on the 24 hour duration of a day. 
This concept of Horas takes into account 7 lordships – that of the 7 planets. The seven planets, their horas and the seven week days together form a concept which is found in written form in Yavana Jataka and here lies the clue for #how_seven_days_of_week got their names and the particular order in which they are used today.

At the first glance, Hora are similar to the ordinary hours which all of us are used to. A Planetary Day consists of 24 Horas, and an ordinary day consists of 24 hours.

But Planetary Day begins at the moment of sunrise in the given place, while ordinary day begins at midnight. Since the moment of sunrise is generally different for different places, every place on the Earth has its own Planetary Day, while ordinary day is the same for all the places in the same time zone.

Ordinary hours always have the same continuity (60 minutes), while the length of Hora varies around the year, and Day Hora is usually not equal to Night Hora. Vedic Astrology divides each day into 24 Horas.

Hora is one of the most important part of mahurat and the basis for determining the order of the weekdays.

From Sunrise to sunset these 24 Horas are ruled by seven planets, Lord of first hora at Sunrise is always the Lord of that particular day.  

Now the question arises, #why_is_the_day_coming_after_Sunday_is_named_Monday, Why not other day. 
It all depends upon the distance of Planets from sun and their respective speed w.r.t. to earth, the rule used for allocating houses to planets. (Saturn is slowest).
To understand this, we will first have to understand the positions of the planets, in the space. In astrology, the respective position of planets are given as under – Saturn, Jupiter, Mars, Sun, Venus, Mercury and Moon.

 

Therefore, Saturn is the highest or the farthest planet. Below the Saturn is Jupiter, below Jupiter is Mars, below the Mars is Sun, below the Sun is Venus, below Venus is Mercury, and below Mercury is Moon.

Since there are 24 Horas in a day combined with night, therefore, each Hora consists of an hour. The ‘Lord’ of each Hora is a planet from the nearest lower orbit.

Horas are determined on the basis of srishtyadi ahargana (number of terrestrial days passed from the day of creation), with the first hora being ruled by Sun/Surya.The calculations for sristyadi ahargana can be found in Surya Siddhanta.

The Lord of the first HORA is the Sun. In the beginning of the creation, the Sun was visible first and all life started with the appearence of Sun for that very reason, it has been considered as the lord of the first Hora and the first day has been named after it.

 The next Hora is named after ‘Shukra’ (Venus, which is the lord of the second Hora, and whose orbit is just below the Sun.

The lord of the third Hora is ‘Budha’ (Mercury) whose orbit is just below that of Shukra (Venus).

The lord of the fourth orbit is the Moon (Chandrama), whose orbit is below that of Venus and so on.

In this way, the lord of the 24th HORA is again Mercury. The following chart clearly shows the positions of the planets (horizontally) in order, and the days of the week (vertically) in order.

Start LMT	Hora	Sun	Mon	Tue	Wed	Thurs	Fri	Sat
6 AM	1	Sun	Mon	Mar	Mer	Jup	Ven	Sat
7	2	Ven	Sat	Sun	Mon	Mar	Mer	Jup
8	3	Mer	Jup	Ven	Sat	Sun	Mon	Mar
9	4	Mon	Mar	Mer	Jup	Ven	Sat	Sun
10	5	Sat	Sun	Mon	Mar	Mer	Jup	Ven
11	6	Jup	Ven	Sat	Sun	Mon	Mar	Mer
Noon	7	Mar	Mer	Jup	Ven	Sat	Sun	Mon
1 PM	8	Sun	Mon	Mar	Mer	Jup	Ven	Sat
2	9	Ven	Sat	Sun	Mon	Mar	Mer	Jup
3	10	Mer	Jup	Ven	Sat	Sun	Mon	Mar
4	11	Mon	Mar	Mer	Jup	Ven	Sat	Sun
5	12	Sat	Sun	Mon	Mar	Mer	Jup	Ven
6	13	Jup	Ven	Sat	Sun	Mon	Mar	Mer
7	14	Mar	Mer	Jup	Ven	Sat	Sun	Mon
8	15	Sun	Mon	Mar	Mer	Jup	Ven	Sat
9	16	Ven	Sat	Sun	Mon	Mar	Mer	Jup
10	17	Mer	Jup	Ven	Sat	Sun	Mon	Mar
11	18	Mon	Mar	Mer	Jup	Ven	Sat	Sun
M.N	19	Sat	Sun	Mon	Mar	Mer	Jup	Ven
1 AM	20	Jup	Ven	Sat	Sun	Mon	Mar	Mer
2	21	Mar	Mer	Jup	Ven	Sat	Sun	Mon
3	22	Sun	Mon	Mar	Mer	Jup	Ven	Sat
4	23	Ven	Sat	Sun	Mon	Mar	Mer	Jup
5	24	Mer	Jup	Ven	Sat	Sun	Mon	Mar

From the Hora chart, it is quite clear that the Moon is the lord of the first Hora (Hour) of the second day(Monday), hence the next day after Sunday is called Monday.

Similarly, the lord of the first Hora of the third day is Mars (Tuesday),

The lord of the first Hora of the fourth day is Mercury (Wednesday),

The lord of the first Hora of the fifth day is Jupiter (Thursday),

The lord of the first Hora of the sixth day is Venus (Friday) and

The lord of the first Hora of the Seventh day is Saturn (Saturday).

Therefore, the name of the days in order are Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday.

Note the following:

1.        The lord of the fourth Hora starts the first hour of the next day

2.        The lord of the sixth Hora starts the first hour of the night.

The order of the days in the week is obtained based on the lordship of the first hour of the day. This is an important concept in Jyotish.

Remember the following:

•   Rule # H01 The lord of the first hour of the day is the lord of the day called Dinesa or Varesha. We get two (perhaps more) corollaries from this rule which is the foundation of Hora shastra.

•       Cor#01: the lord of the first day (or first Hora) of a month becomes the Lord of the Month and is called Masadhipati (Lord of Month)

•       Cor#02: the Lord of the first day (or first Hora) in a Year becomes the lord of the year and is called and Varsheshwara (Lord of the Year).

Use of Hora
Each hour of the day carries the influence of one of the planets, knowledge of these "planetary hours" could lead to greater effectiveness in action, based on proper planning.

1. The Hora has a direct influence on the houses and this knowledge is extensively used by the intelligent astrologer in planning his activities.

2. All activities started during the Hora ruled by the Lord of the related Bhava (House) in the birth chart shall surely fructify.

3. Similarly, activities started during the Hora of the Badhakesh from the concerned Bhava shall suffer obstruction and activities started during the Hora of the Rogesh (8th Lord) from the concerned Bhava shall suffer annihilation

Generally, the hora of Saturn and Mars should be approached carefully. Saturn's hora can bring delays, obstacles and pressures, but may also be a great time for doing business. Mars sometimes brings arguments or harshness, but may also bring good ambitious energy.

The hora of Venus and Jupiter, on the other hand, are usually favorable for most activities. But it must be understood that each person will respond differently to a planetary hora based on the specific indications in their natal horoscope.