Type a name in any script, a term, a question, or a combination such as “Saturn in the 7th”.
In short. A chart is a map of the sky at birth: twelve signs, the sign rising in the east, and the nine grahas placed in them.
Varāhamihira opens the Bṛhat Jātaka with the word horā. Horā is the old name for the subject. He derives it from aho-rātra, which means day and night. The subject is the sky as it turns through a day.
He adds that a chart shows the ripening of deeds done in earlier lives. The classical authors describe tendencies and expect an astrologer to weigh them.
The zodiac and the ayanāṁśa
The zodiac is a belt of twelve signs, each 30° wide, along the Sun’s apparent path. Indian astrology counts the signs from a fixed point among the stars. Its zodiac is sidereal. Western astrology counts from the spring equinox, which drifts slowly backwards against the stars.
The difference between the two is the ayanāṁśa. It is a little over 24° now and grows by about a degree every 72 years. This app uses the true Citrāpakṣa ayanāṁśa, measured from the star Spica (Citrā). You can choose another in the Script control, such as Lahiri, Raman or Krishnamurti. The ayanāṁśas differ by up to about 2.3°. This can move a graha into the next sign or nakṣatra.
A graha at 10° Vṛṣabha in the Western zodiac is 30° + 10° = 40° from the start of Meṣa. Take away an ayanāṁśa of 24°: 40° − 24° = 16°. This is 16° Meṣa in the sidereal zodiac. The graha moves back one sign.
The lagna and the houses
The lagna, or ascendant, is the sign rising on the eastern horizon at birth. All twelve signs rise in about a day. The lagna therefore changes roughly every two hours, and an accurate birth time is necessary to find it. The lagna stands for the person. Every house is counted from it.
The texts used here count whole signs as houses. The lagna’s sign is the 1st house, the next sign is the 2nd, and so on round the zodiac. A graha anywhere in a sign is in that sign’s house. Other house systems exist, but classical Parāśarī astrology uses whole signs.
With Karka rising, Karka is the 1st house, Siṁha the 2nd, Kanyā the 3rd, and so on to Mithuna, the 12th. A graha at 29° Siṁha is in the 2nd house, and so is a graha at 1° Siṁha.
The grahas and their positions
Jyotiṣa uses nine grahas. They are the Sun, the Moon, the five planets visible to the eye, and Rāhu and Ketu, the two points where the Moon’s path crosses the Sun’s.
Three things give a graha’s position: its sign, its degree in that sign, and the nakṣatra that degree falls in. A nakṣatra is one of 27 lunar mansions.
Two ways of drawing the chart
South and North India draw the chart differently. Both show the same positions. Use the South · North switch to change between them.
| South Indian chart | North Indian chart | |
|---|---|---|
| What stays fixed | the signs, each in its own box | the houses |
| Where to start | Meṣa is the second box of the top row | the top diamond is always the 1st house |
| Direction | the signs run clockwise | the houses run anticlockwise |
| The lagna | marked in whichever box it falls | the top diamond; each box carries the number of its sign |
Astrologers also draw divisional charts (vargas), which cut each sign into smaller parts. The navāṁśa is the varga most used. Astrologers also measure the grahas’ strength, time events with daśās, and look for yogas. A yoga is a named combination. Each of these topics has a chapter below.