ಪಂಚಾಂಗ ಎಂದರೇನು | What a panchanga actually is

Panchanga means “five limbs”. The five are tithi, vara, nakshatra, yoga and karana, and between them they describe where the sun and the moon stand on a given day. Everything else an almanac prints, the festivals, the auspicious and inauspicious hours, the month and year names, is derived from those five.

Why both the sun and the moon

Most calendars pick one. The Gregorian calendar follows the sun and ignores the moon, so its months have drifted free of the lunar cycle entirely. The Islamic calendar follows the moon and ignores the sun, so Ramadan moves through all the seasons.

The Hindu calendar refuses to choose. The months are lunar, running from one new moon to the next, and the year is solar, tied to the sun’s passage through the zodiac. These do not divide evenly: twelve lunar months come to about 354 days against the solar year’s 365. The calendar absorbs the mismatch by inserting a thirteenth month, the adhika masa, roughly every third year. That is why Ugadi and Deepavali fall on different Gregorian dates each year but never drift out of their seasons.

What the five limbs measure

Four of the five come from a single quantity: the angle between the moon and the sun as seen from the earth.

• Tithi is that angle divided into thirty parts. It is the lunar day.
• Karana is the same angle divided into sixty, so a karana is half a tithi.
• Nakshatra is where the moon alone stands, against twenty-seven equal divisions of the sky.
• Yoga is the sum of the two longitudes, also divided into twenty-seven. It has no direct physical meaning; it is a derived quantity used for its own purposes.
• Vara is simply the weekday, the one element that needs no astronomy at all.

The awkward part: these do not line up with days

A tithi averages a little under twenty-four hours, but it varies between about nineteen and twenty-six depending on how fast the moon is moving. So a tithi does not begin at sunrise and end at the next. It begins whenever the angle reaches the right value, which may be the middle of an afternoon.

This is the source of almost every disagreement about which day a festival falls on. The convention is that a day carries the tithi that is running at sunrise, but different observances use different reference moments: Janmashtami wants the tithi at midnight, Ganesha Chaturthi at midday, Pradosha at dusk, Sankashti Chaturthi at moonrise. A short tithi can begin after one sunrise and end before the next, touching no sunrise at all, in which case it takes the day it begins on.

An almanac that only prints the tithi at sunrise is hiding this. Anudina shows you the start and end times, so you can see for yourself where a date came from.