Last updated
The astronomical basis of the Hindu lunar day

In Vedic timekeeping, a tithi is a [duration of two faces of moon that is observed from earth], known as milа̄lyа̄ (𑐩𑐶𑐮𑐵𑐮𑑂𑐫𑐵𑑅, मिलाल्याः) in Nepal Bhasa, [1] or the time it takes for the longitudinal angle between the Moon and the Sun to increase by 12°. In other words, a tithi is a time-duration between the consecutive epochs that correspond to when the longitudinal-angle between sun and moon is an integer multiple of 12°. Tithis begin at varying times of day and vary in duration from approximately 19 to approximately 26 hours. [2] Every day of lunar month is called tithi.



image to understand the calculation of tithi Tithi Calculation.jpg
image to understand the calculation of tithi

A Hindu muhurta (forty-eight minute duration) can be represented in five attributes of Hindu astronomy namely, vara the weekday, tithi, nakshatra the Moon's asterism, yoga the angular relationship between Sun and Moon and karana half of tithi.

Tithi plays an important role along with nakshatra in Hindus' daily as well as special activities in selecting the muhurta. There are auspicious tithis as well as inauspicious tithis, each considered more propitious for some purposes than for other.

There are 30 tithis in each lunar month, named as:

Sl.NoKrishna paksha
(dark fortnight)
Shukla paksha
(bright fortnight)
Deity and properties[ citation needed ]
1Prathama / Padyami Prathama / PadyamiThe presiding deity of the first lunar day is Agni and it is good for all types of auspicious and religious ceremonies.
2Dwitiya / Vidiya Dwitiya / VidiyaVidhatr or Brahma rules this lunar day and is good for the laying of foundations for buildings and other things of a permanent nature.
3Tritiya / Thadiya Tritiya / ThadiyaGauri is the lord of this day and is good for the cutting of one's hair and nails and shaving.
4Chaviti Chaviti Yama/Ganapati is lord of the 4th lunar day, which is good for the destruction of one's enemies, the removal of obstacles, and acts of combat.
5Panchami Panchami The Naaga or Serpents rule this day, which is favourable for administering medicine, the purging of poisons, and surgery.
6Shashthi Shashthi Karttikeya presides over this day and is favourable for coronations, meeting new friends, festivities, and enjoyment.
7Saptami Saptami The 7th lunar day is ruled by Surya; one may begin a journey, buy conveyances, and deal with other such things of a movable nature.
8Ashtami Ashtami The Rudra rule this day, which is good for taking up arms, building of one's defenses, and fortification.
9Navami Navami The Ambikaa rules this day, which is suitable for killing enemies, acts of destruction, and violence. Inauspicious for ceremonies and journeys.
10Dasami Dashami The day is ruled by Dharmaraja and is auspicious for acts of virtue, religious functions, spiritual practices, and other pious activities.
11Ekadasi Ekadashi Rudra rule this day; fasting, devotional activities, and remembrance of the Supreme Lord Vishnu are very favourable. This day has special religious significance in Hinduism and Jainism—usually observed by fasting.
12Dvadasi Dwadashi The Vishnu or Aditya rules this day, which is auspicious for religious ceremonies, the lighting of the sacred fire, and the performance of one's duties.
13Trayodasi Thrayodashi The day is ruled by Kamadeva and is good for forming friendships, sensual pleasures, and festivities.
14Chaturdashi Chaturdashi Kali rules this day, suitable for administering poison and calling of elementals and spirits.
15 Amavasya
(new moon)
Purnima or Paurnami
(full moon)
The Pitru-devas rule the New Moon, suitable for the propitiation of the Manes and performance of austerities. Purnima is ruled by Moon and is suitable for merry making and fire sacrifice.

Related Research Articles

The term dark moon describes the last visible crescent of a waning Moon. The duration of a dark moon varies between 1.5 and 3.5 days, depending on its ecliptic latitude. In current astronomical usage, the new moon occurs in the middle of this dark period, when the Moon and Sun are in conjunction. This definition has entered popular usage, so that calendars will typically indicate the date of the "new moon" rather than the "dark moon".

Lunar day Time for Moon to complete one rotation on its axis

A lunar day is the period of time for Earth's Moon to complete one rotation on its axis with respect to the Sun. Due to tidal locking, it is the time the Moon takes to complete one orbit around Earth plus about 2.2 more Earth days to return to the same Moon phase. The lunar day is roughly 29 1/2 Earth days, the length of a lunar month, the time of which includes a full day-night cycle.

The Hindu calendar, Panchanga or Panjika is one of various lunisolar calendars that are traditionally used in the Indian subcontinent and Southeast Asia, with further regional variations for social and Hindu religious purposes. They adopt a similar underlying concept for timekeeping based on sidereal year for solar cycle and adjustment of lunar cycles in every three years, but differ in their relative emphasis to moon cycle or the sun cycle and the names of months and when they consider the New Year to start. Of the various regional calendars, the most studied and known Hindu calendars are the Shalivahana Shaka found in the Deccan region of Southern India, Vikram Samvat (Bikrami) found in Nepal, North and Central regions of India – all of which emphasize the lunar cycle. Their new year starts in spring. In regions such as Tamil Nadu and Kerala, the solar cycle is emphasized and this is called the Tamil Calendar and Malayalam calendar and these have origins in the second half of the 1st millennium CE. A Hindu calendar is sometimes referred to as Panchangam (पञ्चाङ्ग), which is known also known as Panjika in Eastern India.

Panchangam Traditional Hindu calendar

A panchāngam is a Hindu calendar and almanac, which follows traditional units of Hindu timekeeping, and presents important dates and their calculations in a tabulated form. It is sometimes spelled Panchāngamu, Pancanga, Panchanga, Panchaanga, or Panchānga, and is often pronounced Panchāng. Panchangas are used in Jyotisha.

Vaisakha 2nd month of the Hindu calendar

Vaisakha is a month of the Hindu calendar that corresponds to April/May in the Gregorian Calendar. In Indian national calendar, Vaisakha is the second month of the year. It is the first month of the Vikram Samvat calendar, Odia calendar, Punjabi calendar, Assamese calendar and the Bengali calendar. This month lies between the second half of April and the first half of May.

Vikram Samvat or Bikram Sambat and also known as the Vikrami calendar, is the historical Hindu calendar used in the Indian subcontinent. It is the official calendar of Nepal. In India, it is used in several states. The traditional Vikram Samvat calendar, as used in India, uses lunar months and solar sidereal years. The Nepali Bikram Sambat introduced in 1901 AD, also uses a solar sidereal year.


Falgun or Phalgun or Phagun is the eleventh month of the year in the Bengali calendar, the Assamese calendar, and the Nepali calendar. In the revision of the Bengali calendar used in Bangladesh since October 2019, the month has 29 days in common years or 30 in leap years of the Gregorian calendar. In the previous version of the calendar, used in Bangladesh from 1987 through October 2019, Falgun had 30 days in common years or 31 days in leap years. The month has 29 or 30 days, based on the true movements of the Sun, in the old non-reformed Bengali calendar, still used in West Bengal, and in the Nepali calendar.

Amavasya Last day of the dark lunar fortnight

Amāvásyā is the lunar phase of the new moon in Sanskrit. Indian calendars use 30 lunar phases, called tithi in India. The dark moon tithi is when the Moon is within 12 degrees of the angular distance between the Sun and Moon before conjunction (syzygy). The New Moon tithi is the 12 angular degrees after syzygy. Amāvásyā is often translated as new moon since there is no standard term for the Moon before conjunction in English.

The Vira Nirvana Samvat (era) is a calendar era beginning on 7 October 527 BCE. It commemorates the Nirvana of Lord Mahaviraswami, the 24th Jain Tirthankara. This is one of the oldest system of chronological reckoning which is still used in India.

Ekadashi Eleventh day of the lunar fortnight

Ēkādaśī ("Eleventh"), also spelled as Ēkādaśi, is the eleventh lunar day (tithi) of each of the two lunar phases which occur in an vedic calendar month - the Shukla Pakṣa and the Kṛṣṇa Pakṣa It is according to the Vedic medical texts of Ayurveda and is mentioned in detail in many original treatises such as Charaka Samhita and Susruta Samhita.

Nepal Sambat Nepalese Traditional Calendar

Nepal Sambat is the lunisolar calendar used by the people of Nepal. The Calendar era began on 20 October 879 AD, with 1142 in Nepal Sambat corresponding to the year 2021–2022 AD. Nepal Sambat appeared on coins, stone and copper plate inscriptions, royal decrees, chronicles, Hindu and Buddhist manuscripts, legal documents and correspondence. Though Nepal Sambat is declared a national calendar and is used widely in Nepal, it is mostly used by the Newar community whereas Bikram Sambat (B.S) remains the dominant calendar throughout the country.

Kārtika (month) * 8 (for Hindu calendar) * 7 (for Bengali calendar)th month of the * Hindu calendar * Bengali calendars

Kārtika is a month in the Hindu calendar that typically overlaps October and November. In the Nepali calendar, Maithili, and Bengali, it is the 7th month, in the Tamil calendar it is the 8th month.

Paksha , thwa and gа̄ in Nepal Bhasa, refers to a fortnight or a lunar phase in a month of the Hindu lunar calendar.

Hasta is a nakshatra in Hindu astrology having a spread from 10° – 23° 20′. It corresponds to the stars of Alpha, Beta, Delta, Gamma, and Epsilon-Corvi in the constellation Corvus (constellation).

Ashtami is the eighth day (Tithi) of Hindu lunar calendar.

Adhik Maas is an extra month in the Hindu calendar that is inserted to keep the lunar and solar calendars aligned.

Choghadiya Panchang is a Vedic Hindu calendar. Showing Dina, Nakshatra, Tithi, Yoga, Karana for every day, with automatic adjustment for any city in the world based on Sunset and sunrise of every city in the world.

Anuradha (nakshatra)

Anuradha is the seventeenth nakshatra in Hindu astrology having a spread from 3°20' to 16°40'. Anuradha is ruled by Shani (Saturn). Mitra is the deity for Anuradha Nakshatra. Anuradha is a fragile nakshatra with the shakti power of granting abundance. Anuradha rules the breasts, stomach, womb and bowels.

Lunar month Time between successive new moons

In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month.

Astronomical basis of the Hindu calendar Applied astronomy of ancient India

The Hindu calendar is based on a geocentric model of the solar system. A geocentric model describes the solar system as seen by an observer on the surface of the earth.


  1. Kapali, Rukshana. "नेपाल संवत् - नेपाल सम्बत" (PDF). Nepal Sambat. Retrieved 3 November 2021.
  2. Defouw, Hart; Robert Svoboda (2003). Light on Life: An Introduction to the Astrology of India . Lotus Press. p.  186. ISBN   0-940985-69-1. Shukla paksha -inpublisher:icon.