Vedic Astrology :
The word “Vedic” means “pertaining to Vedas". Vedas are the sacred scriptures of, what is known today as, Hinduism and they are supposed to contain knowledge of all subjects. Moreover, astrology in particular is supposed to be a “Vedaanga” (which means a limb of Vedas). In particular, it is said to be the eye of the Vedas.
Jyotish is considered to be one of the Vedangas (part of Vedas) propounded by lord Brahma by the scientific study of which human beings can accomplish virtue. Jyotish shastra or the science of Vedic astrology, is a compilation of 4,00,000 verses (vide Narada Purana, II.50.2). Vedic astrology has mainly three branches – Siddhanta (the principle), Jataka or Hora (astrology for individuals) and Samhita (astrology for masses).
• Siddhanta, also known as Ganita, deals with the mathematical calculations, the methodology of calculating planetary positions, knowledge about time, place, direction, lunar and solar eclipses, their rising and setting, planetary movements, conjunctions, retrogression, etc.
• Jataka (Hora) deals with the techniques of interpretation of horoscopes of individuals. It describes signs, planets, their qualities, family situations/ circumstances at the time of birth, arishta (mishaps), longevity of the native, different dasha systems and their results, profession (sources of livelihood), ashtakavarga, varied types of yogas, results of planetary positions in different houses, signs, nakshatras, aspects of planets, planetary combinations, female horoscopy, circumstances at the time of death, cases of unknown birth time, etc. The term ‘Hora’ has been applied to ‘Jataka’ or natal astrology, as well as to the ‘Muhurta’ or electional astrology (i.e., selecting the appropriate moment to commence an undertaking).
• Samhita is that branch of astrology which is related to masses and is a compilation of varied subjects like the results of rising and setting of planets, appearance of different types of comets, varied types of chakras, predicting about rainfalls, earthquakes, natural disasters and epidemics, results of planetary movements on kingdoms, nations, masses and commodities, etc.
The Geocentric System
It is a human tendency to refer to other things in relation to oneself. Sitting in a moving train, we see things passing by the train – trees, farms, hutments, etc. A common question arises in our mind – which is the station coming next? At the back of our mind we do know that it is not the station which is going to come, it is the train which will reach the next station. Similarly we refer to the rising and setting of the Sun. But we do know that it is not the Sun which is rising or setting, it is the spin of the earth which makes it appear so.
Because we feel stationary on the solid earth, the sky seems to spin around us in complicated ways. In our quest to understand what we see, our ancients had evolved a most innovative and powerful tool.
As nothing is stationary in the universe, whether it is a satellite or a planet or even a star, it is convenient to imagine our position in the universe – the earth – as its centre and the whole of the universe moving around us in constant motion. Thus considering the relative positions and movements of all heavenly bodies with respect to the earth is the Geo-centric system. On the other hand, when we consider the relative position of planets (including the earth) in respect of the Sun, it forms the basis of the Helio-centric system. Vedic astronomy and astrology are essentially geo-centric in their concept.
The earth is spherical and rotates from west to east around its axis. The axis of the earth is an imaginary line which, passing through its centre, connects its two poles, the north pole and the south pole. Another imaginary line running across the largest circumference of the earth, equidistant from its poles and running in an east-west direction, is called the equator.
The Celestial Sphere
Think of the sky as a great, hollow, crystalline sphere surrounding the earth. Imagine the stars to be attached to the inside of the sphere like thumbnails stuck in the ceiling. The sphere takes one day to rotate, carrying the Sun, the Moon, the planets and the stars from east to west. We know that the sky is not a great, hollow, crystalline sphere. The stars are scattered through space at different distances, and it isn’t the sky that rotates once a day. It is rather the earth that rotates once in a day around its axis. It is convenient as a model of the sky. This model of the sky, the Celestial sphere, is an imaginary hollow sphere of very large radius (infinity) surrounding the earth and to which the stars seem to be attached. On this imaginary sphere the celestial equator, the celestial poles, and other reference points are marked as they are done on the earth; these represent the extensions of the equator and the poles, etc., of the earth into infinity.
The earth takes one year to complete its rotation around the Sun. From the earth, it appears that the Sun moves around the earth. This apparent path of the Sun is known as ecliptic. An imaginary belt of 18 degrees width with ecliptic in its centre is known as the zodiac. Many groups of stars appear to have been studded on this imaginary belt. Vedic astrology recognizes 27 such groups of stars called nakshatras.
The zodiac encircles the earth like a circle consisting of 360 degrees. If this circle is divided into 27 equal parts, each part will be of 13 degrees and 20 minutes arc, known as a nakshatra. Each nakshatra is further divided into 4 quarters (padas or charanas), of 3 degrees and 20 minutes arc each.
Twelve divisions of the zodiac will have an arc of 30 degrees each, known as rashis (or signs).
The above figure shows rising of the Sun in the
eastern horizon. The line passing through the centre of the Sun is the
ecliptic, the apparent path of the Sun created by its ‘revolution’
around the earth during its annual journey. The group of stars, referred
to as the nakshatras, are the fixed reference points in the zodiac used
to locate the position of the Sun, the Moon and other heavenly bodies.
All the planets considered in Vedic astrology for the purpose of
interpretation, do not decline beyond the belt of the zodiac. They may
be on the ecliptic or towards the north or sourth of the ecliptic
depending on their latitude with reference to the ecliptic.
The most crucial point in the division of a circle is to know the starting point of the circle. The point where the ecliptic cuts the celestial equator is known as equinox. There are two such equinoxes – the vernal equinox and the autumnal equinox. When the Sun is passing from the southern hemisphere to the northern hemisphere, it cuts the equator at vernal equinox. When the division of the circle of the zodiac is with reference to vernal equinox as its starting point, the zodiac is referred to as the Sayana (or tropical) zodiac, the divisions of this zodiac into twelve equal parts are the Sayana rashis, and the positions of planets in this zodiac represent the Sayana longitudes of the planets.
The Precession of Equinoxes
If we could watch the sky for a few hundred years, we would discover that the north celestial pole is moving slowly with respect to Dhruva (Polaris) star. The celestial poles and the celestial equator, supposed to be the fixed reference marks, are moving very slowly because of the slow change in the direction of Earth’s axis of rotation. This slow top-like motion is called precession. Earth’s axis sweeps around in a cone, taking almost 26,000 years for each sweep.
Precession is caused by the gravitational pull of the Sun and the Moon. Because earth is not a perfect sphere – it has a slight bulge around its equator – Sun and Moon pull on it, trying to make it spin upright in its orbit. This forces earth’s axis to precess.
The result of this precession is that vernal equinox, the cutting point of the ecliptic and the celestial equator, drifts westward on the ecliptic by an approximate angle of 51 seconds of an arc each year. So we have a new vernal equinox every year and hence a new staring point of the Sayana zodiac. This results in the shifting of the Sayana signs.
The Vedic system does not depend on this shifting zodiac and relies on a fixed point on the zodiac as its starting point. There is no clear cut demarcation of this starting point in the zodiac. Some consider this point to be 180 degrees opposite to the Chitra nakshatra. Some consider it to be slightly to the east of the Revati nakshatra, while still others opine differently.
When the division of the circle of the zodiac is with reference to the Vedic starting point, the zodiac is referred to as the Nirayana (or Sidereal) zodiac, the twelve equal parts are the Nirayana rashis, and the positions of planets in this zodiac represent the Nirayana longitudes of the planets.
The angular difference between the vernal equinox and the Vedic starting point of the zodiac is known as the Ayanamsha. When the Vedic starting point is with reference to Chitra nakshatra, the Ayanamsha is refered to as the Chitrapaksha Ayanamsha. According to this system the first point of Sayana zodiac and Nirayana zodiac coincided in the year 285 A.D. The corresponding value of this Ayanamsha on January 1997 is 23°48'56".
Grahas (planets) :
The words “planet” and “star” are used in a slightly different sense in astrology than in astronomy. For example, Sun (a star) and Moon (a satellite of earth) are called planets in astrology, along with Mars etc. Basically, a graha or a planet is a body that has considerable influence on the living beings on earth. Distant stars have negligible influence on us, but Sun, Moon and planets in the solar system have a great influence on our activities. So the word graha (or planet) is used to describe them.
Seven planets are considered in Indian astrology. They are – Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn. In addition, two “chaayaa grahas” (shadow planets) are considered in Indian astrology – Rahu and Ketu. These are also called “the north node” and “the south node” respectively (or the head and tail of dragon). Rahu and Ketu are not real planets; they are just some mathematical points. Apart from these 9 planets, there are 11 moving mathematical points known as Upagrahas (sub-planets or satellites).
We also have lagna (ascendant), which is the point that rises on the eastern horizon as the earth rotates around itself. In addition, we have some mathematical points known as “special ascendants".
Rahu and Ketu are exalted in Taurus/Scorpio and are also exalted in Gemini and Virgo.
The natural planetary relationships are:
Imagine a belt or a path in the sky, some 18 degrees of are in
width, running around the earth in an east-west direction.
Groups of stars, to all appearance fixed, are studded along this
imaginary belt. Twenty seven (or twenty eightl) such groups of
stars are in Vedic astrology. Because of lack of
apparent motion, these are called as Nakshatras. This imaginary
belt, with nakshatras studded on it, is called the zodiac.
The zodiac forms the reference point for fixing up the position
of any planet or star in the sky. Since it encircles the earth, it
is comprised of 360 degrees. The twenty-seven nakshatras being
evenly placed on it each have a span of 13°2O' arc. The various
nakshatras are numbered from one to twenty-seven.
In contrast to the fixed nakshatras, there are the moving
heavenly bodies called the Grahas. These move along the zodiac
from the west to the east. They derive their name from the
fact that, while moving against the background of the
nakshatras, they appear to get hold of one nakshatra after the
other (graha = to catch hold 00. Vedic astrology recognises nine
grahas. They are the Sun, the Moon, Mars, Mercury, Jupiter,
Venus, Saturn, Rahu and Ketu. Of these, the Sun is a star, the
Moon is a satellite of the earth, Rahu and Ketu are mere
mathematical points on the zodiac, while the remaining ones
Rasis (zodiac signs) :
The positions of all these planets, upagrahas, lagna and special lagnas in the zodiac
are measured in degrees, minutes and seconds from the start of the zodiac (which is a
fixed point in the sky). These positions are measured as seen from earth and they are
called “geocentric positions". These positions are measured in
longitude and sphuta. When watched from earth, the longitude of any planet in the
skies can be from 0°0'0'' (0 degrees 0 minutes 0 seconds) to 359°59'59''. It should be
noted that 0°0'0'' corresponds to the beginning of the zodiac.
Sidereal zodiac is also an imaginary belt of 360 degrees (as viewed from earth), divided into 12 equal parts. Each twelfth part (of 30 degrees) is called sign or rashi.
The zodiac (sky) lasts 360° as mentioned above and it is divided into 12 equal parts.
They are called “rasis” (signs). English names, Sanskrit names, two-letter symbols
and values of the start longitude and the end longitude (in degrees, minutes and
seconds) of all twelve rasis are given in below table.
If a planet is at 221°37', then you can find from above table that it is between 210°0'0'' and 239°59'59''. So, that planet is in Scorpio (or Vrischika). Its advancement from the start of the rasi occupied by is 11°37'. Its position in the zodiac (221°37') is shown by some people by the notation 11°37' in Sc or simply 11 Sc 37. This means “advanced by 11°37' from the start of Sc (Scorpio)".
The whole zodiac is nothing but a manifestation of Lord Vishnu’s body. Aries is the
head. Taurus is the face. Gemini is the arms. Cancer is the heart. Leo is the stomach.
Virgo is the hip. Libra is the space below navel. Scorpio is the private parts.
Sagittarius is the thighs. Capricorn is the knees. Aquarius is the ankles. Pisces is the
feet. These are the limbs that rasis in the natural zodiac stand for. Because we are all part
of the Supreme energy governing this world, the above mapping applies to us too.
For example, we should pay attention to Leo for analyzing stomach problems and to
Pisces for analyzing problems related to feet and so on.
The Sage Parashara gives many details about each rasi. There is a lot of
information we can learn about each sign by delving into this
information. This table has several of the important attributes of each
n Indian Astrology when a zodiac is divided into twelve equal parts, each such part has an extension of 30 degrees of arc. Such a division is called a sign or Rasi.
There are 12 houses of Rasi's.
Lords of Houses
Each Rasi has a planet assigned to it as Lord of the House.
Each planet has a point in the zodiac where it attains maximum strength. The houses where they have the maximum strength are called the houses of exaltation.
Each planet has a point in the zodiac where it has the minimum strength. The houses where the planets have the minimum strength are called the houses of debilitation.
Planets and their debilitated houses
Period of stay of Planets in each House
Types of Houses
Houses or Bhavas:
Another important concept is “house” (Sanskrit name: bhava). In each chart, houses can be found with respect to several reference points and the reference points most commonly employed are lagna and special lagnas. Starting from the rasi occupied by the selected reference point and proceeding in the regular order across the zodiac, we associate each rasi with a house (first, second etc). Always the rasi containing the reference point chosen is the 1st house. Next rasi is the 2nd house. The rasi after that is the 3rd house. We proceed until the 12th house like that.If no reference point is specified when houses are mentioned, it means that lagna is used as the reference.
Our lives here on Earth through our physical bodies are shown through the Bhavas. The Sanskrit term literally means, "Coming into existence, Birth. It is through what is shown through the houses that our karma is born materially. It is here that Purusha is expressed as Prakriti in a world of consequence. Each house has many attributes, yet underneath there is a deeper concept key to that house. Different houses stand for different matters. Looking at the rasis and houses
occupied by various planets, we can say a lot of things about the person.
In Hindu astrology, the natal chart is the bhava chakra (Sanskrit: chakra, 'wheel'.) The bhava chakra is the complete 360° circle of life, divided into houses, and represents our way of enacting the influences in the wheel. Each house has associated karaka (Sanskrit: karaka, 'significator') planets that can alter the interpretation of a particular house.
A “chart” (Sanskrit name: chakra) is prepared with the information of rasis occupied by all planets. For preparing any chart, we need to first determine the rasis occupied by all planets, upagrahas, lagna and special lagnas. In the visual representation of a chart, there are 12 boxes (are some other visual areas) with each representing a rasi. All planets, upagrahas and lagnas are written in the boxes corresponding to the rasis they occupy.
There are 3 popular ways of drawing charts in India:
(1) South Indian style chart ruled by Jupiter (rasi based),
(2) North Indian style diamond chart ruled by Venus (bhava based) and
(3) East Indian style Sun chart ruled by Sun (rasi based).
In rasi-based chart drawing formats, a rasi is always at a fixed position. Ar is always in
one particular position and Ta is in another position and so on. Planets, lagna etc are
placed in the box (or the visual area) representing the rasi occupied by it. In bhavabased
chart drawing formats, a bhava (house) is always at a fixed position. Lagna
(denoted by “Asc” for ascendant) is always in a particular visual area of the chart and
the 2nd, 3rd etc houses are in fixed positions.
Varga chakras (divisional charts)
We saw that charts can be drawn with the information of which planet occupies
which rasi. Based on the longitude of a planet, we can find the rasi occupied by it
and mark its position in rasi chart.
In addition, we have what are known as “divisional charts” (Sanskrit name: varga
chakras). These are based on dividing rasis into 2 parts, 3 parts, 4 parts and so on.
We divide each rasi into n parts and map each part to a rasi again. Based on the rasis
occupied by planets in these divisional mappings, we draw divisional charts (or
harmonic charts). Each divisional chart throws light on a specific area of one’s life.
In each divisional chart, we find houses and analyze the chart as if it were an
The science of Vedic astrology stands on the basis of 4 pillars –
(1) grahas or planets, (2) rasis or signs, (3) bhavas or houses, and, (4) varga chakras
or divisional charts.
In Vedic astrology, the zodiac is divided into 27 nakshatras. Each nakshatra has a
length of 360º/27 = 13º 20'. The first nakshatra, for example, stretches from the
beginning of Aries to 13º 20' in Aries. The second nakshatra stretches from there to
26º 40' in Aries. The third nakshatra stretches from there to 10º in Taurus.
Each nakshatra is again divided into 4 quarters. They are called padas (legs/feet).
The length of a nakshatra pada is 3º 20'.
The zodiac according to Indian Astrology comprises of 360 degrees. There are 27 Nakshatras or constellations in it.Therefore, the value of each constellation is 13 degrees and 20 minutes when measured from the fixed initial point. These 27 Nakshatras(stars) complete the entire circle of 360 degrees of the zodiac. A forecast based on the transit/ correlation/inter - relation of planets in relation to the Nakshatras is more accurate than the results predicted on the basis of any other system.
What is your Nakshatra (star)?
You can find it from the table given below. If you know the longitude of the Moon at the time of your birth in your natal chart calculated according to the Indian/ Vedic system, go to the 3rd column and go down till it lies between the two values given in the row above and below. Your Nakshatra or star would be the one given in the 2ndcolumn the one at the start of range of longitude of your Moon.
Each Nakshatra or star that comes under Indian Astrology has an astronomical name associated with it and which is referred to by the Western Astrologers and Astronomers.
Table with Astronomical name equivalent of Indian Nakshatras.
In lunar calendar, one day stands for one tithi. Tithi or lunar day is a period in which
the difference between the longitudes of Moon and Sun changes by exactly 12°.
When Sun and Moon are at the same longitude, a new lunar month of 30 tithis starts.
As time progresses, Moon will go ahead of Sun. When Moon’s longitude is exactly
12° greater than Sun’s longitude, the first tithi or lunar day finishes and the second
tithi starts. When Moon’s longitude is exactly 24° greater than Sun’s longitude, the
second tithi finishes and the third tithi starts. When Moon’s longitude is exactly 36°
greater than Sun’s longitude, the third tithi finishes and the fourth tithi starts. And so
on. You can see that Sun-Moon longitude differential will be (12 x n)° after exactly n
A lunar month consists of 30 tithis. Each month is divided into two fortnights
(pakshas). During Sukla/Suddha paksha or the brighter fortnight, Moon is waxing.
During this paksha, Moon is ahead of Sun by an amount that is between 0º and 180º.
During Krishna/Bahula paksha or the darker fortnight, Moon is waning. During this
paksha, Moon is ahead of Sun by an amount that is between 180º and 360º.
At the end of a month, Sun-Moon longitude differential will be (12 x 30)°, i.e., 360°.
That means that Moon will finish one cycle around the zodiac and catch up with Sun
again. So Sun and Moon will be at the same longitude again. Then a new month
We can find the tithi running on a day from the longitudes of Sun and Moon using
the following procedure.
(1) Find the difference: (Moon’s longitude – Sun’s longitude). Add 360° if the result
is negative. The result will be between 0° and 360° and will show how advanced
Moon is with respect to Sun.
(2) Divide this result by 12°. Ignore the remainder and take the quotient.
(3) Add 1 to the quotient. You get a number from 1 to 30. That will give the index of
the tithi running.
(4) Refer to Table 3 and find the name of the tithi. There are 15 tithis and the same
tithis repeat in the brigher and darker fortnights. For example, it can be seen from
the table that the 22th tithi out of the 30 tithis is in Krishna paksha and it is
Saptami. So the 22nd tithi is “Krishna Saptami”. We write the classification of
fortnight (Sukla or Krishna) first and then write tithi name. “Sukla Saptami”
stands for “Saptami” in the brighter fortnight (sukla paksha), i.e. the 7th tithi.
“Krishna Saptami” stands for “Saptami” in the darker fortnight (krishna paksha),
i.e. the 22nd tithi.
Add the longitudes of Sun and Moon. Remove 360º from the sum if it is greater than
360º. Divide the sum by the length of one nakshatra (13°20' or 800'). Ignore fractions and take the integer part. Add 1 to it and the result is the index of the yoga running.
Refer to Table 5 and find the yoga corresponding to the index.
Each tithi is divided into 2 karanas. There are 11 karanas: (1) Bava, (2) Balava, (3)
Kaulava, (4) Taitula, (5) Garija, (6) Vanija, (7) Vishti, (8) Sakuna, (9) Chatushpada,
(10) Naga, and, (11) Kimstughna. The first 7 karanas repeat 8 times starting from the
2nd half of the first lunar day of a month. The last 4 karanas come just once in a
month, starting from the 2nd half of the 29th lunar day and ending at the 1st half of the
first lunar day.
Each day starts at sunrise and ends at next day’s sunrise. This period is divided into
24 equal parts and they are called horas. A hora is almost equal to an hour. These
horas are ruled by different planets. The lords of hora come in the order of
decreasing speed with respect to earth: Saturn, Jupiter, Mars, Sun, Venus, Mercury
and Moon. After Moon, we go back to Saturn and repeat the 7 planets.
The first hora of any day (i.e. a period of one hour following sunrise) is ruled by the
lord of the weekday (Sun for Sunday, Moon for Monday, Mars for Tuesday,
Mercury for Wednesday, Jupiter for Thursday, Venus for Friday and Saturn for
Saturday). After that, we list planets in the order mentioned above.
For example, let us take 9:40 pm on a Wednesday on which sunrise was at 6:10 am.
The time elapsed since sunrise is 21:40 – 6:10 = 15:30. So the 16th hour since sunrise
was running then. This is ruled by the 16th planet from Mercury. After subtracting
multiples of 7 from 16, we get 2. So the hora (hour) is ruled by the 2nd planet from
Mercury. From the list given above, we see that the 2nd planet from Mercury is
Moon. So Moon’s hora runs at 9:40 pm.
Panchaanga means “one with 5 limbs”. Almanacs published in India with planetary
positions are traditionally called panchaangas. Along with the planetary positions,
they give the start and end times of tithi, vaara (week day – Sunday, Monday etc),
nakshatra, yoga and karana running on each day. These five are the limbs of
When we choose a muhurta (an auspicious time for starting a venture), we should
choose an auspicious tithi, vaara, nakshatra, yoga and karana.
Dasa systems are a hallmark of Vedic astrology. Vedic astrology has hundreds of
dasa system. Each dasa system divides one’s life into periods, sub-periods, sub-subperiods
and so on. All the periods are ruled by different planets or rasis. Some dasa
systems are planet-based and some are rasi-based. Each dasa system is good at
showing events of a specific nature. For each dasa system, we have some standard
rules, based on which we analyze the natal chart and attribute different results to
different periods and sub-periods. Each dasa system comes with rules for dividing
one’s life into periods and sub-periods and rules for attributing different results to
different periods, based on the planetary positions in the natal chart. These periods
are called “dasas” or “mahadasas” (MD). Sub-periods are called “antardasas” (AD).
Sub-sub-periods are called “pratyantardasas” (PD).
Some dasas are good at showing matters related to longevity and death. They are
called “ayur dasas” (dasas of longevity). Some dasas are good at showing general
results. They are called “phalita dasas” (dasas of general results).
Mind is a very important part of our existence and Moon governs it. Some dasas are
computed based on the nakshatra occupied by Moon and they are called “nakshatra
dasas”. Some dasas are based on the rasis occupied by planets and they are called
The dasha system shows which planets will be ruling at particular times in Hindu astrology. There are several dasha systems; however, the primary system used by astrologers is the Vimshottari dasha system. The first maha dasha is determined by the position of the natal Moon. Each maha dasha is divided into subperiods called bhuktis. Vimshottari dasha lengths are:
Gochara (Sanskrit: gochara, 'transit'.) In Hindu astrology, a natal chart shows the actual positions of the grahas at the moment of birth. Since that moment, the grahas have continued to move around the zodiac, interacting with the natal chart grahas. This period of interaction is called gochara.
Kalasarpa Yoga is a dangerous yoga. If all planets (excepting Uranus, Neptune, Pluto) are 1-side of Rahu & Ketu, it becomes Kala-Sarpa Yoga.
The Vedic System of Calculating the Ascendant
The most important point in the construction of a horoscope is the Ascendant. The ascendant is the point of cutting of the ecliptic by the eastern horizon of a place.
The earth spinning on its axis in a linear movement takes 24 hours to complete one rotation. But what exactly is the duration of a day? There are many types of days prevalent.
Sidereal day: The time taken by earth to spin one complete rotation of 360 degrees on its axis. Average duration of one sidereal day is 23 hrs, 56 min, 4.091 sec.
Savana day: The duration of time between one sunrise to another sunrise is a Savana day. For people living in northern hemisphere, from winter solstice day onwards, the sunshine hours (dinamana) increases and night hours (ratrimana) decreases. As the sunrise every day is earlier than the previous day, the duration of the savana day is less than 24 hours till the Sun reaches its maximum declination at summer solstice. After that the dinamana reduces and the ratrimana increases. Since the sunrise of every day is later than the previous day, the duration of the savana day is more than 24 hours till it reaches the winter solstice again.
Mean Solar Day: The average of all the days of a year. It’s duration is equal to 24 hours.
The Vedic system recognises a day as the duration
of time from one sunrise to the next sunrise. This span, known
as a Savana day, is measured in units of ghatis. One Savana day
is equal to 60 ghatis and each ghati is divisible into 60 palas
Rashimana (Oblique Ascension)
Rashimana is the rising periods of signs of the zodiac. As there are twelve equally divided signs of the zodiac and it takes approximately 24 hours for all the signs to rise, therefore, one sign should take about two hours to rise in the eastern horizon. But it’s not so. As the plane of the ecliptic is inclined at an angle of 23.5 degrees to the plane of the celestial equator, the rising time of different signs is not uniform. The time taken by different groups of signs at the equator is given in Table 1.
Rashimana values are calculated for Sayana signs and are measured in units of Asus. One unit of Asu is equivalent to 4 seconds of sidereal time. Rashimana values vary from one latitude to another. These values once calculated for any place do not change from year to year.
Charakhandas (Ascensional Differences)
Variations in the rising of different signs at different
latitudes can be calculated with the help of Charakhandas or ascensional
differences for those latitudes.
Signs of Long Ascension and Short Ascension
For people living in the northern hemisphere of the earth, on the day of winter solstice, when the Sun is at zero degrees Sayana Capricorn, the sunshine hours are the shortest. With the rising of the Sun, sign Capricorn rises in the eastern horizon followed by other signs in sequence. At the time of sunset, the point rising at the eastern horizon would be 180° opposite the Sun’s longitude (thus zero degrees Cancer). Therefore, during the daytime signs Capricorn to Gemini rise in the shortest duration of time, while at night the signs Cancer to Sagittarius take the longest duration of time.
When the Sun is at summer solstice (zero degrees Sayana Cancer) during the daytime signs Cancer to Sagittarius spend the longest duration of time to rise and during night signs Capricorn to Gemini take the shortest duration of time.
Sign which takes longer time in rising than the time taken by same sign at the equator, is the sign of long ascension and the sign which takes shorter time in rising is the sign of short ascension. Signs Capricorn to Gemini are short ascension signs while Cancer to Sagittarius are long ascension signs for norther latitudes. Reverse is the case for people living in the southern latitudes.
As the latitude of the observer increases, the duration of signs of long ascension become much longer while the duration of signs of short ascension become much shorter.
Calculation of rising times of different signs (Rashimana) for a particular place
After knowing the Charakhandas of a particular place, we can calculate the rashimana of different signs. Add the Charakanda values, in asus, to the rashimana values at the equator in their respective groups for signs of long ascension and subtract the Charakhandas from their respective groups for signs of short ascension.
Correlation of the earth with the Zodiac
Calculation of ascendant for any given moment is an effort to establish a relationship between the horizon of the observer on the earth with the zodiac.
The earth is spinning continuously on its axis. To an observer, being located on the surface of the earth, it appears that the earth is stationary and the sky with all the stars and heavenly bodies is drifting towards the west after rising in the east.
To establish a relationship of the earth with the zodiac, we have to refer to some identifiable point on the zodiac. The rising, setting or the meridian passage of this point is to be observed to find out the actual position of this point at any given moment of time for the place of location of the observer. Once we know the position of one point of the zodiac, we can relate the other points of the zodiac with respect to this identifiable point.
This identifiable point could be a star or a planet or the vernal equinox (zero degrees Sayana Aries point) of the zodiac. When we observe the passing of the Vernal Equinox on the meridian of a place, it is zero hours Sidereal time for that place. Sidereal time at any given moment indicates the time elapsed since the vernal equinox crossed the meridian of that place.
The Indian system makes use of the position of the Sun in the zodiac to establish a link between the earth and the zodiac. At the time of sunrise, the centre of the Sun is touching the eastern horizon. Sunrise is considered to be the beginning to the day and that day remains in force till the next sunrise. The duration of this day is considered to be equal to sixty ghatis. One ghati is roughly equal to 24 minues of time.
The longitude of the Sun is identical with the cusp of the sign rising at the time of sunrise. A track of the number of ghatis and palas passed since sunrise is kept and is called Ishtakaala.
Since the rashimana values are for Sayana signs, the longitude of the Sun is also considered in Sayana values.
Inputs to calculate the Ascendant
In order to calculate the cusp of the ascendant,
we need the following:
Steps to Calculate the Ascendant
The following steps describe the method of calculation of the ascendant for a given place at a given date and time. For example, let’s calculate the ascendant rising at Gurdaspur, India (latitude 32°N02' longitude 75°E31') on April 1, 1997 at 12.00 hours IST.
Step 1. Calculate the Charakhandas
On the ‘Hindu Dial’, measure the length of the mid-day shadow, on the day of the equinox, of a shanku of 12 units length.
The derived values of 450, 360 and 150 are the charakhandas for I, II and III groups of signs respectively.
Step 2. Calculate the Rashimana
The Rashimana for different groups of signs at the equator are:
Step 3. Find out the Sunrise time
From the ephemeris, calculate the sunrise time on the given date for the place of birth. For Gurdaspur the sunrise time is 6h:20m:40s (IST).
Step 4. Find out the Sayana Sun
Again from the ephemeris, calculate the position of Sayan Sun at the time of sunrise. If the available ephemeris provides the longitudes of planets in nirayana values, add the ayanamsha to the Sun’s longitude to get the Sayana value. The nirayana longitude of the sun at the time of sunrise on April 1, 1997 is 11s17°31'16". Adding to this the ayanamsha value on the given date, i.e., 23°49'06", we get the Sayana longitude of the Sun at the time of sunrise as 0s11°20'22". This also indicates the longitude of the ascendant at the time of sunrise.
Step 5. Find out the Ishtakala
Ishtakala is the time elapsed since the time of sunrise to the time of birth. Traditionally the time of birth is recorded in ishtakala only. Since in our example the time of birth is in hours-minutes, etc., it can be converted to ishtakala by subtracting the time of sunrise from the time of birth.
Time of birth : 12h:00m:00s
Step 6. Cusp of the Ascendant
From Step 4 above, we know the sign that the sun is in at sunrise and, therefore, the cusp of the sign rising at the time of sunrise. The duration of this sign being known (Step 2), it is possible to work out how much of this sign has yet to rise above horizon and how much time it will take to do so.
Thus we get the cusp of ascendant at 12 noon as
Cancer 16°02'30". This is the Sayana value. Reduce the
ayanamsha from this value to obtain the cusp of the ascendant
in nirayana value. Thus the nirayana ascendant would be: