The Indian Calendar
The Indian calendar is of 29.5 days. A month is divided into two halves called Paksha of 15 Thithees (Lunar days) each. The first half beginning with a full moon and is called Purnimavasya and the second half beginning with the new moon is called Amavasya or Bahaulvashya.
The fortnight beginning with the new moon is called Shuklpaksha and the dark half is called Krishnapaksha. The calendar normally consists of 12 lunar months. This makes only 354 days, thus to cater for the difference with a solar year, a thirteenth month was added to the calendar after every 30 lunar months. This leap month was called Dvitiya Asadha or DvitiyaSravanna. It was added after asadha or sravanna month. Thus each second or third year had thirteen months.
Indian Months
The Indian calendar is divided into 12 months given below.
| Indian calendar month | Gregorian calendar month |
|---|---|
| Chaitra | March – April |
| Vaishakh | April – May |
| Jyaistha | May – June |
| Ashadh | June – July |
| Sharavan | July – August |
| Bhadrapada or Parusthapada | August – September |
| Ashivan or Asvayuja | September – October |
| Kartikka | October – November |
| Margasirsha or Agrahayana | November – December |
| Pausa or Taisa | December – January |
| Magha | January-February |
| Phalgun | February – March |
However, during Vedic times the months were called Madhu, Madhava, Shukra, Suchi, Nabhas, Nabhasya, Isa, Urja, Sahas, Tapas, and Tapashya.
Indian Seasons
A group of two months was called Ritu. The six seasons were Vasantha ( Spring, March-May), Grishma (Summers, May – July), Varsha (Rains, July – September), Sarad (Autumn, September – November), Hemantha (Winters, November – January), and Sishir (Cool-season, January – March.)
Indian Dates
Indian dates are normally given in the order of month, paksha and tithi, and the abbreviation sudi or badi is used for the bright or dark halves of the month e.g. Chaitra sudi7 means , seventh day from the new moon of the month of Chaitra.
Eras followed by Indians
The Indian calendar is divided into 12 months given below.
| Vikramaditya Era | This started in 58BC. It was started by Emperor Vikramaditya to celebrate his victory over the Sakas and driving them out of Ujjain. |
| Sakas Era | This was started by a Saka King on his return to Ujjain in 78AD. |
| Gupta Era | It was started by Emperor Chandra Gupta in 320 AD. |
| Harsh era | Started by Raja Harshavardhana of Kannauj in 606 AD. |
| Kalachuri Era | Started in 248 AD by a small dynasty of Central India called Traikutaka. |
| Lakshmana Era | Started in Bengal in 1119 AD. |
| Lichivi and Nevar Era of Nepal | Started in 110 Ad and 878 AD respectively. |
| Kollam Era of Malabar | Started in 825 AD. |
| Buddha Era | Started in 544 BC. |
| Mahavir Era | Started in 528 BC. |
Of all the above, the Saka and Vikrama are the most widely used eras.
Weights, Measures & Distances
The various measurements given in the Manu Smriti and still in use in some of the remote villages and areas of India are:
| Goldsmith weights |
*1 tola is approximately 10 grams |
| Length |
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| Time |
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Cosmology & Cosmic Time
According to the scriptures, the cosmos passes through cycles of time within cycles of time for all eternity over an enormous period of time called Mahakalpa. During the cosmos evolves and declines and again evolves only to decline once again. This cycle is divided into four periods of Ashankyeya.
The basic cycle is called Kalpa i.e ‘Day of Brahma‘ which is equal to 4320 million earthly years. His night is equal to the day, 360 such day and night of Brahma is equal to “One year of Brahma”. The life of each Brahma is 100 such years, thus as per the Hindus, the life of the universe is 311,040,000 million years. After this another great Brahma takes birth.
In each cosmic day or Kalpa the Brahma creates the Universe and gathers it in his lap at night. Each Kalpa has 14 Manvantras or secondary cycles of 306,720,000 earth years.
In each of these secondary cycles, one new Manu appears. We are now in the 7th Manavantra of the Kalpa. The present Manu is called Vaivasvata.
Each Manvantra contains 71 Mahayugs (1000 Mahayugs make one Kalpa.) Each Mahayug has four yugs called Karta, Treta, Dwapar, and Kalyug. The duration of each of these is 4800, 3600, 2400, and 1200 years of GOD (each year of God = 360 human years.) We are in the Kalyug which started in 3120 BC i.e when the Mahabharat war started. The Kalyug will finish in 428898 AD.
The Planets & Stars
As per Rig Veda, heaven was divided into 27 Nakshatras based on the position of the moon. The full cycle of the moon was divided into 27 1/2 days and later this was corrected by adding another nakshatra.
The nakshatras are given below.
| Ashwini | Bharani | Krattka |
| Rohini | Mragasiras | Ardra |
| Punarvasu | Pusya | Asleesa |
| Magha | Purva-Phalguni | Uttara-Phalguni |
| Hastha | Chitra | Swati |
| Vishaka | Annuradha | Jyestha |
| Maula | Purvasadha | Uttarasadha |
| Abhijeet | Sharvana | Dhanishta or Sravistha |
| Satabishaj | Purva-bhadrapadda | Uttara-bhadrapadda |
The seven planets which could be seen by naked eyes were named Surya (Sun), Chandra (Moon), Budha (Mercury), Shukra (Venus), Mangal (Mars), Brahspati (Jupitar), and Shani (Saturn). later two more planets which though could not be seen by the naked eyes. These were Rahu and Ketu. So way back, before the invention of the telescope, our astronomers had known that there were nine planets.
If you wish to read more about Ancient India, here are some other articles you can look at.