Hindu calendar

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(list)
Wide use Astronomical · Gregorian · ISO
Calendar Types
Lunisolar · Solar · Lunar

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Display types and applications Perpetual calendar · Wall calendar · Economic calendar

The Hindu calendar used in ancient times has undergone many changes in the process of regionalization, and today there are several regional Indian calendars, as well as an Indian national calendar.

Most of these calendars are inherited from a system first enunciated in Vedanga Jyotisha of Lagadha, a late BCE adjunct to the Vedas, standardized in the Surya Siddhanta (3rd century CE) and subsequently reformed by astronomers such as Aryabhata (499 CE), Varahamihira (6th c. CE), and Bhaskara (12th c. CE). There are differences and regional variations abound in these computations, but the following is a general overview of Hindu lunisolar calendar.

Day

The Hindu calendrical day starts with local sunrise. It is allotted five "properties", called anga-s. They are:

1. the tithi active at sunrise
2. the vaasara or weekday
3. the nakshatra in which the moon resides at sunrise
4. the yoga active at sunrise
5. the karana active at sunrise.

Together these are called the panchānga-s where pancha means "five" in Sanskrit. An explanation of the terms follows.

Tithi

The (anticlockwise) angular distance between the sun and moon as measured from the earth along the ecliptic (circle on the sky in which the sun, moon and planets seem to move) can vary between 0° and 360°. This is divided into 30 parts. Each part ends at 12°, 24° etc. The time spent by the moon in each of these parts (i.e. the time taken for the angular distance to increase in steps of 12° starting from 0°) is called one tithi.

The month has two paksha-s or fortnights. The first 15 tithi-s constitute the bright fortnight or shukla paksha and the next 15 tithi-s constitute the dark fortnight or krishna paksha. tithi-s are indicated by their paksha and ordinal number within the paksha. The 15th tithi of the bright fortnight (full moon) is called pūrnimā and the 15th tithi of the dark fortnight (new moon) is called amāvāsyā.

The tithi in which the moon is at the time of sunrise of a day is taken to be the tithi for the day.

Vaasara

Vaasara, often abbreviated as vaara in Sanskrit-derived languages, refers to the days of the week, which are possibly of Sumerian/Babylonian origin[1], and bear striking similarities with the names in many cultures:

Following are the Hindi and English analogues in parentheses

1. Ravi vāsara (ravi-vaara or Sunday; ravi = sun)
2. Soma vāsara (som-vaara or Monday; soma = moon)
3. Mangala vāsara (mangal-vaara or Tuesday; mangala = Mars)
4. Budha vāsara (budh-vaara or Wednesday; budh = Mercury)
5. Guru vāsara (guru-vaara or Bruhaspati-vaara or Thursday; vrihaspati/guru = Jupiter)
6. Shukra vāsara (shukra-vaara or Friday; shukra = Venus)
7. Shani vāsara (shani-vaara or Saturday; shani = Saturn)

There are many variations of these names in the regional languages, mostly using alternate names of the celestial bodies involved.

Nakshatra

Nakshatras
Ashvinī
Bharanī
Kṛttikā
Rohinī
Mrigashīrsha
Ārdrā
Punarvasu
Pushya
Āshleshā
Maghā
Pūrva Phalgunī
Uttara Phalgunī
Hasta
Chitrā
Svātī
Vishākhā
Anurādhā
Jyeshtha
Mūla
Pūrva Ashādhā
Uttara Ashādhā
Shravana
Dhanistha
Shatabhishā
Pūrva Bhādrapadā
Uttara Bhādrapadā
Revatī

The ecliptic is divided into 27 nakshatras, which are variously called lunar houses or asterisms. These reflect the moon's cycle against the fixed stars, 27 days and 7¾ hours, the fractional part being compensated by an intercalary 28th nakshatra. Nakshatra computation appears to have been well known at the time of the Rig Veda (2nd–1st millennium BCE).

The ecliptic is divided into the nakshatras eastwards starting from a reference point which is traditionally a point on the ecliptic directly opposite the star Spica called Chitrā in Sanskrit. (Other slightly-different definitions exist.) It is called Meshādi or the "start of Aries"; this is when the equinox — where the ecliptic meets the equator — was in Aries (today it is in Pisces, 28 degrees before Aries starts). The difference between Meshādi and the present equinox is known as ayanāngsha or fraction of ecliptic. Given the 25,800 year cycle for the precession of the equinoxes, the equinox was directly opposite Spica in 285 CE, around the date of the Surya Siddhanta[2][3].

The nakshatra-s with their corresponding regions of sky are given below, following Basham[4]. As always, there are many versions with minor differences. The names on the right-hand column give roughly the correspondence of the nakshatra-s to modern names of stars. Note that nakshatra-s are (in this context) not just single stars but are segments on the ecliptic characterised by one or more stars. Hence there are more than one star mentioned for each nakshatra.

Ashvinī β and γ Arietis
Bharanī 35, 39, and 41 Arietis
Krittikā Pleiades
Rohinī Aldebaran
Mrigashīrsha λ, φ Orionis
Ārdrā Betelgeuse
Punarvasu Castor and Pollux
Pushya γ, δ and θ Cancri
Āshleshā δ, γ, ε, η, ρ, and σ Hydrae
Maghā Regulus
Pūrva Phalgunī δ and θ Leonis
Uttara Phalgunī Denebola
Hasta α to ε Corvi
Chitrā Spica
Svātī Arcturus
Vishākhā α, β, γ and ι Librae
Anurādhā β, δ and π Scorpionis
Jyeshtha α, σ, and τ Scorpionis
Mūla ε, ζ, η, θ, ι, κ, λ, μ and ν Scorpionis
Pūrva Ashādhā δ and ε Sagittarii
Uttara Ashādhā ζ and σ Sagittarii
Shravana α, β and γ Aquilae
Dhanishthā α to δ Delphinis
Shatabhishaj γ Aquarii
Pūrva Bhādrapada α and β Pegasi
Uttara Bhādrapada γ Pegasi and α Andromedae
Revatī ζ Piscium

An additional 28th intercalary nakshatra, Abhijit (alpha, epsilon and zeta Lyrae - Vega - between Uttarasharha and Sravana), is in between Uttarashada and Sravana. Last two (third and fourth) Padas of Uttrashada and first two (first and second) Padas of Sravana are considered to be Abhijit.

The nakshatra in which the moon lies at the time of sunrise of a day is the nakshatra for the day.

Yoga

First one computes the angular distance along the ecliptic of each object, taking the ecliptic to start at Mesha or Aries (Meshādi, as defined above): this is called the longitude of that object. The longitude of the sun and the longitude of the moon are added, and normalized to a value ranging between 0° to 360° (if greater than 360, one subtracts 360.) This sum is divided into 27 parts. Each part will now equal 800' (where ' is the symbol of the arcminute which means 1/60 of a degree.) These parts are called the yoga-s. They are labeled: