A solstice is the time when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around 20-22 June and 20-22 December. In many countries, the seasons of the year are defined by reference to the solstices and the equinoxes.
Hindu astrology, also called Indian astrology, Jyotisha and, more recently, Vedic astrology, is the traditional Hindu system of astrology. It is one of the six auxiliary disciplines in Hinduism that is connected with the study of the Vedas.
The Hindu calendar, also called Panchanga, 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 and the Vikram Samvat (Bikrami) found in Nepal and the North and Central regions of India – both 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 (पञ्चाङ्गम्), which is also known as Panjika in Eastern India.
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.
Sankranti refers to the transmigration of the sun from one zodiac to another in Indian astronomy. In Saurmanavarsha, there are twelve Sankrantis corresponding with twelve months of a year. The Sankrantis can be broadly classified into four main categories: Ayan (Solstice), Vishuva (Equinox), Vishnupadi and Shadshitimukhi sankrantis.
Nakshatra is the term for Lunar mansion in Hindu astrology and Buddhist astrology. A nakshatra is one of 27 sectors along the ecliptic. Their names are related to a prominent star or asterisms in or near the respective sectors. In essence, a nakshatra simply is a constellation. Every nakshatra is divided into four padas related to the Char Dham, a set of four pilgrimage sites in India.
Vikram Samvat, also known as the Vikrami calendar is a national Hindu calendar historically used in the Indian subcontinent and still also used in several Indian states and Nepal. It is a solar calendar, using twelve to thirteen lunar months each solar sidereal years. The year count of the Vikram Samvat calendar is usually 57 years ahead of the Gregorian calendar, except during January to April, when it is ahead by 56 years.
The September equinox is the moment when the Sun appears to cross the celestial equator, heading southward. Because of differences between the calendar year and the tropical year, the September equinox may occur from September 21 to 24.
The March equinox or northward equinox is the equinox on the Earth when the subsolar point appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth. The March equinox is known as the vernal equinox in the Northern Hemisphere and as the autumnal equinox in the Southern Hemisphere.
The term Uttarāyaṇa is derived from two different Sanskrit words – "uttaram" (North) and "ayanam" (movement) – thus indicating the northward movement of the Sun. In the Gregorian calendar, this pertains to the "actual movement of the sun with respect to the earth." Also known as the six month period that occurs between the winter solstice and summer solstice. According to the Indian solar calendar, it refers to the movement of the Sun through the zodiac. This difference is because the solstices continually precess at a rate of 50 arcseconds per year due to the precession of the equinoxes, i.e. this difference is the difference between the sidereal and tropical zodiacs. The Surya Siddhanta bridges this difference by juxtaposing the four solstitial and equinoctial points with four of the twelve boundaries of the rashis.
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 Surya Siddhanta is a Sanskrit treatise in Indian astronomy dated to 4th to 5th century, in fourteen chapters. The Surya Siddhanta describes rules to calculate the motions of various planets and the moon relative to various constellations, diameters of various planets, and calculates the orbits of various astronomical bodies. The text is known from a 15th-century CE palm-leaf manuscript, and several newer manuscripts. It was composed or revised probably c. 800 CE from an earlier text also called the Surya Siddhanta. The Surya Siddhanta text is composed of verses made up of two lines, each broken into two halves, or pãds, of eight syllables each.
Ekadashi is the eleventh lunar day (tithi) of the waxing and waning lunar cycles in a Vedic calendar month. Ekadashi is popularly observed within Vaishnavism one of the major paths within Sanatan Dharma. Followers offer their worship to the god Vishnu by fasting or just symbolically; the idea was always to receive self-discipline and the benefits of fasting and it was connected to the way of life via Sanatam Dharma practices.
Vedanga Jyotisha, or Jyotishavedanga, is one of earliest known Indian texts on astrology (Jyotisha). The extant text is dated to the final centuries BCE, but it may be based on a tradition reaching back to about 700-600 BCE.
Gaurabda is the name of the moon calendar used by Gaudiya Vaishnavism as part of the liturgy.
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.
Gargiya-jyotisha, also known as Garga-samhita, is a 1st-century Indian Sanskrit-language astrological treatise attributed to Garga. The oldest extant text of the Indian astrology (jyotiḥśāstra), it is written in form of a dialogue between Garga and Kraushtuki.
The nirayana system is a traditional Indian system of calendrical computations in which the phenomenon of precession of equinoxes is not taken into consideration. In Indian astronomy, the precession of equinoxes is called ayana-calana which literally means shifting of the solstices and so nirayana is nir- + ayana meaning without ayana. Ayanacalana refers to the continuous backward movement of the point of intersection of the ecliptic and the celestial equator. In contrast, the Indian systems of calendrical computations which take into consideration the effects of precession of equinoxes are called sayana systems.
In Indian astronomy, yoga (also called nityayoga) is a period of time, of varying lengths, during which the sum of the nirayana longitudes of the Sun and the Moon increases by an amount of 13 degrees 20 minutes (or, equivalently, 800 minutes). While considering the sum, when the sum is 360 degrees or more, then the angle 360 degrees is subtracted from the sum to make the sum an angle between 0 degree and 360 minutes. Consider a moment T1 when the sum of the longitudes of the Sun and the Moon is 0 degree and let T2 be the next immediate moment when the sum of the longitudes of the Sun and the Moon is 13 degree 20 minutes. The duration of time between the moments T1 and T2 is the first yoga. Similarly, let the next immediate moment when the sum of the longitudes of the Sun and Moon is 26 degrees 40 minutes. The duration of time between the moments T2 and T3 is the second yoga. The third, fourth and higher yoga-s are defined in a similar way. Since 27 X 13 degrees 20 minutes = 360 degrees, at the end-moment of the 27th yoga, the sum of the nirayana longitudes of the Sun and Moon would be 0 degree. The numbering of the yoga-s then starts afresh from that point. It appears that the astronomical yoga-s are in no way related to any astronomical phenomena. S. B. Dikshit in his Bhāratīya Jyotiṣ Śāstra observes: "It is not known what planetary position in the sky is indicated by yoga, and it is useful only in astrology."
In Indian astronomy, a karaṇa is a half of a tithi. It is the duration of time in which the difference of the longitudes of the Sun and the Moon is increased by 6 degrees. A lunar month has 30 tithi-s and so the number of karaṇa-s in a lunar month is 60. These sixty karaṇa-s are not individually named. Instead, the originators of the concept have chosen 11 names to be associated with the karaṇa-s which means several karaṇa-s will be associated with the same name. Of these 11 names, four are fixed or immovables in the sense that they are associated with four unique karaṇa-s in a lunar month. These constant names are Śakuni, Catuṣpāda, Nāga and Kimstughna. The remaining seven names are variable or movable in the sense that there are several karaṇa-s associated with each of them. These names are Bava, Bālava, Kaulava, Taitila, Gara, Vaṇij and Vṛṣṭi.
