Why festival dates move

The civil calendar is solar. A tithi is lunar. A festival tied to a tithi therefore falls on a different English date each year. The stable fact is the tithi rule. The year's date is what you get when a panchang applies that rule at a place. This note gives the usual North Indian rules. It does not give a date for 2026, and it does not give a clock time.

If you want a year list, name the panchang Astro should follow, for example the Rashtriya Panchang or the sheet your family already uses, and name the city. The next draft can cite that source line by line. Until then, the rules below are the thing that does not move.

Why the English date cannot be memorised

A solar year is the Earth's return to the same seasonal point. A lunar month is thirty tithis, a little under thirty civil days. Twelve lunar months fall short of a solar year, so an extra month is inserted from time to time, and the English dates of lunar festivals walk. People who learned "Diwali is in October or November" have already met the walk. The learning that lasts is the tithi, not the weekday they happened to see last year.

Sunrise still matters. Two cities can wear different tithis on the same English morning when a tithi ends near dawn. A festival dated for a port city is not automatically the festival morning in Dumka. The rule is portable. The printed date is local.

New moon and full moon are the hinges of several festivals. The lamps mark the hinges, not a year.

Diwali's new moon, and the nights beside it

Lakshmi Puja is the new moon. North Indian panchangs call that new moon Kartik Amavasya. Amanta panchangs often call the same new moon Ashwin Amavasya. The night is the same. The month label is the school's.

The usual cluster around that night, in the North Indian count, is also a set of tithis rather than a set of English dates. Dhanteras is the Krishna Trayodashi before that new moon. Naraka Chaturdashi, often called Chhoti Diwali, is the Krishna Chaturdashi, the day before the new moon. The day after the new moon is Shukla Pratipada, kept as Govardhan or Annakut. Shukla Dwitiya, the day after that, is Bhai Dooj. In the amanta naming, those two bright tithis open the month that the amanta school calls Kartik. The sequence of nights does not change when the month label does.

Diwali's stable fact is the new moon. The English date is what a panchang computes for a city.

Chhath after that new moon

The usual Jharkhand and Bihar sequence sits on the bright fortnight that follows Diwali's new moon. Nahay-khay is on Chaturthi. Kharna is on Panchami. The evening arghya is on Shashthi. The morning arghya is on Saptami. In both month systems that Shashthi is Kartik Shukla Shashthi. The river, the lamp, and the standing at dusk belong to those tithis. A printed English week is only the result of applying them at a place.

Chhath's evenings and mornings follow a tithi sequence. The drawing has no date on it.

Holi, Navratri, Raksha Bandhan, and the solar hinge

Holika Dahan falls on the full moon of Phalguna. The colour festival is the next morning. The month name of that next morning depends on whether the panchang ends the month at the full moon or at the new moon, so this note does not add a second tithi label. The full moon is the rule that both schools can point at.

Sharad Navratri begins on Ashwin Shukla Pratipada. The nine days run with that bright fortnight. Vijayadashami is Ashwin Shukla Dashami. Raksha Bandhan is Shravana Purnima, the full moon of Shravana.

Makar Sankranti is not a tithi. It is the moment the Sun enters sidereal Makara. The minute belongs to the solar calculation. This beta does not print it, and this note does not guess the civil date. Remembering "around the middle of January" is a memory of recent years, not a muhurat.

The festivals this note will not date

Janmashtami and Maha Shivaratri are left undated here on purpose. More than one tithi rule is in live use. Some counts of Krishna's birthday follow Bhadrapada Krishna Ashtami. Others keep a different observance. Shivaratri is a Krishna Chaturdashi, and the month is not the same in every regional calendar. Picking one and printing an English date would pretend the choice had been made. A date waits until you say which panchang Astro should follow.

No English date for 2026 is in this catalog. The panchang page cannot yet apply these rules to a city. When it can, the citation should be the sheet, the city, and the tithi, in that order.

What a city list will have to show

When a year list is allowed, each line needs four fields and no extras: the festival's tithi rule, the city, the panchang named as the source, and the civil date that source gives for that city. A line with a date and no source is the kind of line this catalog refused. A line that copies last year's weekday forward is the same refusal. Adhik maas, the extra lunar month some years insert, is exactly why a weekday memory fails. The list should say whether that year has an extra month, in the words of the chosen panchang, rather than hide it inside a date. Until that list exists, the safe share is the tithi rule and the city, with the English date left blank on purpose.

A note on Astro is for understanding. It is a matter of belief and reflection. It is not a promise about health, death, money, or the law.

What Astro is, in this beta: https://astro.lawazia.tech/about