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Kshaya masa

How can a lunar month name be skipped?

Rarely, a lunar month holds two Sankrantis and one month name goes unused. See the cases of 1963, 1983 and 2123, each with an extra month on either side.

01 · Two sign changes in one month

In winter a lunar month can outlast a solar month and hold two Sankrantis.

The Sun moves fastest in December and January, so a solar month can be shorter than a lunar one. A lunar month that starts just before one Sankranti can then end just after the next. It holds two names’ worth of Sankranti, and one month name goes unused.

Lunar months and Sankrantis, 1963 to 1964Two rows: the Sun’s sidereal signs with each Sankranti marked, and the lunar months from new Moon to new Moon, with a month holding two Sankrantis in red and a month holding none in gold. Adhika Kartika, 17 Oct to 16 November 1963, holds no Sankranti, the month from 16 November 1963 to 16 December 1963 holds two Sankrantis and Adhika Chaitra, 14 Mar to 12 April 1964, holds no Sankranti.SANKRANTIS (DASHED) AND NEW MOONS, 1963 to 1964The Sun’s signLeoVirgoLibraScorpioCapricornAquariusPiscesAriesLunar months, new Moon to new MoonAshwinKartikaPaushaMaghaPhalgunaOct 1963Dec 1963Feb 1964Apr 1964
1963 to 1964Adhika Kartika, 17 Oct to 16 November 1963, holds no Sankranti, the month from 16 November 1963 to 16 December 1963 holds two Sankrantis and Adhika Chaitra, 14 Mar to 12 April 1964, holds no Sankranti
Sankrantis and new Moons from the site’s ephemeris, sidereal, IST. The engine names each lunar month from the Sun’s sign at its starting new Moon.

The opposite of an extra month

A lunar month is named from the Sankranti inside it. Usually there is exactly one. When there is none the month is an extra, Adhika, month. The reverse can also happen: a lunar month that contains two Sankrantis. It has a claim to two names, and the year loses one month name. Such a month is called Kshaya (क्षय, “loss”).

It needs a solar month shorter than the lunar month around it. The Sun moves fastest in early January, when Earth is nearest the Sun, so the solar months around then last about 29.4 days, while a lunar month can last up to about 29.8. A lunar month that begins just before one Sankranti in that season can end just after the next.

How rare it is

Searching the site’s ephemeris from 1900 to 2149, sidereal and with the site’s ayanamsa, finds three lunar months that hold two Sankrantis:

  • the month from 16 November to 16 December 1963, which held the Sun’s entries into Scorpio at 15:47 IST on 16 November and into Sagittarius at 06:24 on 16 December, within hours of the new Moons at either end;
  • the month from 14 January to 13 February 1983;
  • the month from 18 December 2123 to 16 January 2124.

In each case the same lunar year also had an Adhika month a few months before and another a few months after. With one month name lost and two extra months added, such a year still runs to thirteen lunar months.

The intervals, 19 and 141 years, show how uneven the cycle is. Because the Sankranti and the new Moon can be minutes apart, the result depends on the ayanamsa and on the precision of both times; calendars using other conventions do not all list the same years.

How calendars name it

Traditions handle the lost name differently, for example by joining the two names for the one month. The site’s engine names every lunar month from the Sun’s sign at its starting new Moon, which gives the Kshaya month the name of the month before the skipped one and does not mark it as Kshaya; the next such month is in 2123, so no current date is affected. The lunar month guide lists the ordinary names.

See today’s lunar month on the Delhi Panchang, or explore another topic in Learn.