What a Panchang Is: The Five Limbs and Their Astronomy

A panchang is a daily readout of the sky: five separate astronomical measurements - tithi, vara, nakshatra, yoga and karana - computed for your location and listed with the exact time each one ends. The word itself says so: pancha (five) plus anga (limbs). Nothing in those five limbs is arbitrary. Each is a precise statement about where the sun and moon are, and the tradition has tracked them for well over two thousand years because pujas, vrats and muhurats are all timed against them. The panchang on Purohit.app is computed from planetary positions using the Swiss Ephemeris, the same astronomical library used by observatory-grade software, so what follows is also a description of what our own engine calculates every day.

The five limbs at a glance

Limb	What it measures astronomically	How many
Tithi	Each 12° step in the angle between moon and sun	30 per lunar month
Vara	The weekday, counted sunrise to sunrise	7
Nakshatra	The moon's position among 27 equal divisions of the ecliptic	27
Yoga	The combined longitude of sun and moon, in 27 divisions	27
Karana	Half a tithi - each 6° step of the same angle	11 names, 60 slots per month

Tithi: the moon's angle from the sun

Stand outside on any evening and the moon's phase tells you roughly how far it has pulled away from the sun in the sky. The tithi makes that exact. Take the moon's longitude, subtract the sun's, and every 12 degrees of that growing gap is one tithi. At 0 degrees the two are together - that is amavasya, the new moon. At 180 degrees they are opposite - purnima, the full moon. Thirty steps of 12 degrees complete the 360-degree cycle, giving fifteen tithis in the waxing fortnight (shukla paksha) and fifteen in the waning (krishna paksha).

Because the moon moves through those 12 degrees at a varying speed, a tithi is not a fixed length of time - it can run from about 20 hours to nearly 27. That single fact explains most of the panchang's apparent quirks, and it deserves its own discussion, which we give it in a companion post on tithis.

Vara: the weekday, but counted from sunrise

Vara is the simplest limb - Somavara is Monday, Mangalavara is Tuesday, and so on - but with one difference from the civil calendar: the Hindu day runs from sunrise to the next sunrise, not midnight to midnight. A puja performed at 4 a.m. on a civil Tuesday still belongs to Monday's vara. The weekday names themselves are a fossil of real astronomy: the seven visible "planets" of the ancient sky (sun, moon, Mars, Mercury, Jupiter, Venus, Saturn) were assigned to the hours of the day in order of their apparent speed, and the planet ruling the first hour after sunrise named the day. The same scheme produced Sunday-through-Saturday in the West, which is why the two systems match planet for planet.

Nakshatra: the moon's address among the stars

The ecliptic - the band of sky the sun, moon and planets travel through - is divided into 27 equal arcs of 13°20' each, and each arc is a nakshatra, anchored to star groups like Rohini, Pushya and Anuradha. The day's nakshatra is simply the arc the moon currently occupies. Since the moon takes about 27.3 days to circle the sky against the stars, it spends roughly one day in each nakshatra, which is why the nakshatra changes about once a day in the panchang. Nakshatras carry enormous weight in the tradition: your janma nakshatra (the moon's nakshatra at birth) shapes naming and matching customs, and muhurat selection leans on the day's nakshatra heavily.

Yoga: a combined reading of sun and moon

Yoga is the least intuitive limb and the most purely mathematical. Add the sun's longitude to the moon's longitude, take the total around the 360-degree circle, and divide it into 27 parts of 13°20' - the same size as a nakshatra division. Each part is one of the 27 yogas, from Vishkambha to Vaidhriti. Where tithi tracks the difference between sun and moon, yoga tracks their sum, so it advances faster than either body alone. The tradition reads certain yogas, such as Vyatipata and Vaidhriti, as unsuitable for new beginnings, and panchang makers have computed them faithfully for centuries.

Karana: half a tithi

A karana is half a tithi - each 6-degree step of the moon-sun angle. There are 60 such half-steps in a lunar month but only 11 karana names: seven "movable" karanas (Bava, Balava, Kaulava, Taitila, Gara, Vanija, Vishti) that cycle through eight times each, and four "fixed" ones (Shakuni, Chatushpada, Naga, Kimstughna) that appear once per month around amavasya. The one most people meet in practice is Vishti, also called Bhadra, which the tradition sets aside as a time to avoid starting auspicious work - purohits routinely check for it when fixing a muhurat.

Why everything has an end-time, not a date

Notice what all five limbs have in common: each is defined by a moving angle crossing a threshold. The moon does not wait for midnight to move 12 degrees. A tithi can end at 09:41 in the morning or 11:58 at night; a nakshatra can change during lunch. So the panchang cannot say "today is Panchami" the way a calendar says "today is the 14th" - it says "Panchami until 14:32, then Shashthi", because that is when the moon actually crosses the line. This is why every entry on a daily panchang page carries an end-time, why the times shift from city to city with local sunrise, and why a printed calendar that flattens tithis into whole days will sometimes disagree with the sky. The tradition never intended tithis to be calendar days. It intended them to be what they are: live coordinates of the sun and moon, read fresh each morning.