Vedic astrology basics quiz: practice 0

Many Western astrologers use the tropical (sayana) zodiac, tied to the seasons; Vedic astrology uses the sidereal (nirayana) zodiac, tied to the stars. The gap between the two is called the ayanamsa. To convert, subtract the ayanamsa from the tropical position.

The hero table shows the same moment in both zodiacs. For that date the ayanamsa is about 23.7 degrees (Skybond uses the True Chitra Paksha ayanamsa).

Walk through one row, the Sun. Its tropical position is about 19.7 degrees Aquarius.

Subtracting 23.7 degrees gives a negative number, so borrow a full sign and count back. The result is 26 degrees Capricorn.

The Moon works the same way: 10.8 degrees Virgo minus 23.7 degrees is 17 degrees Leo. The ascendant: 5.9 degrees Leo minus 23.7 degrees is 12 degrees Cancer.

All three moved back one sign for the same reason: each tropical position was less than about 24 degrees into its sign, so subtracting pushed it over the boundary into the previous sign.

A position more than about 24 degrees into a tropical sign stays in the same sign after conversion. So the shift changes some signs and not others, chart by chart.

The Vedic ascendant (lagna) is the sign rising on the eastern horizon at the moment and place of birth. Houses are counted from it.

The moon sign (janma rasi) is the sign the Moon occupies at birth. The sun sign is the sign the Sun occupies.

Light on Life, by Hart de Fouw and Robert Svoboda, puts the difference in one line: 'While Western astrology assigns pre-eminence to the Sun sign, Jyotish awards that position to the ascendant'. Each system is read within its own frame; this page follows the Vedic frame.

Skybond uses the sidereal zodiac with the True Chitra Paksha ayanamsa and whole-sign houses, where one sign equals one house. That is why the sample chart's houses and signs line up one to one, and why reading it is a matter of naming signs.

The bar chart uses a logarithmic scale, so each step covers a much larger span of time than it looks. Read the labels, not the bar lengths alone.

The lagna completes the whole zodiac in a day, about two hours per sign. The Moon changes sign every two to three days, about two and a quarter days on average. The Sun spends about a month in each sign.

This is why the lagna needs an exact birth time. Shift a birth by an hour or two and the ascendant may already be the next sign, which changes where every house falls.

The Sun changes sign only about once a month, so the sun sign rarely depends on the birth time. The Moon sits between the two, changing sign every few days.