Tithi in the Hindu Vedic sky culture

[kishorekumar62]

The Hindu Vedic sky culture implements Zodiac and Lunar stations. I propose adding a Tithi implementation. This helps to read the tithi at any given time visually and effortlessly.

By definition, tithi is similar to lunar stations except that it is synodic. Hence, this scale will rotate with the Sun being 0 degrees always.

While the Zodiac and Lunar stations are anchored by Spica at 180 degrees, tithi would be anchored by the Sun at 0 degrees.

[gzotti]

I have read something about tithi, but not enough to implement. Does it relate to the hour angle of the sun then? How many are there? How are they counted? etc.

[kishorekumar62]

Oh...I can see how that could be a problem :-)

tithi is a synodic measure of time. It is temporal, but there is a spatial definition as you will see below.

The Moon is the astronomical marker for a tithi.

Every 12 degree increase in elongation of the Moon (starting from a New Moon) marks the passing of a tithi. So there are 30 tithi, each marking off 12 degrees of elongation. Since the measure starts with the New Moon, the position of the Sun is always 0 degrees.

Each tithi is labeled with a tuple <lunar phase, tithi number> where

• lunar phase is either waxing or waning (sanskit terms are used - shukla / krshna)
• tithi number is the sanskrit words for 1st, 2nd, 3rd,...,15th (prathama, dvitiya, tritita...). 15th is treated differently but I will not go into that now.

E.g. shukla prathama, shukla dvitiya, shukla tritiya,...krshna prathama, krshna dvitiya, krshna tritiya...

There is a subdivision of a tithi - called "karana". That is half a tithi, i.e., a 6 degree increase in elongation of the Moon. This is analogous to the "pāda" of the Hindu lunar stations.

When I was making the following video, I felt that a tithi scale would have been useful. In this video, I am simulating the <waxing, 9th tithi>.

Here is a long video where I explain tithi using a Stellarium simulation, starting at 14:23.

I should point out that, unlike the zodiac and lunar stations which are relevant to all planets and stars, tithi is by definition relevant only with the Moon. But it is an important calendric element and culturally very relevant to Hindus.

Key difference from zodiac and lunar stations: tithi is a synodic scale, to be read only with the Moon. Does it make sense to implement?

[gzotti]

Ah yes, the other lunar coordinate. It has been a few years, but in the Calendars plugin I have implemented the Indian calendars (according to the R&D book), Tithi is one of the data items we already provide for the "New Hindu Lunar" calendar. It is not visualized as coordinate grid or tickmarks along the ecliptic etc., though.

[kishorekumar62]

Correct 👍. I am requesting for that visualization. Pls consider. Yahoo Mail: Search, organise, conquer On Thu, 26 Mar 2026 at 19:18, Georg ***@***.***> wrote: Ah yes, the other lunar coordinate. It has been a few years, but in the Calendars plugin I have implemented the Indian calendars (according to the R&D book), Tithi is one of the data items we already provide for the "New Hindu Lunar" calendar. It is not visualized as coordinate grid or tickmarks along the ecliptic etc., though. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>