LUNAR MONTHS

A solar year has about 365.2425 days, but a lunar year only has about 355 days. Once in every 3 years, this difference accumulates to one month and an extra lunar month comes. New lunar month starts whenever Sun and Moon are at the same longitude. Then Moon will go ahead of Sun and, after about 29-30 days, he will catch up with Sun again. A new lunar month will start again. These lunar months go by special names. The name of a lunar month is decided by the rasi in which Sun-Moon conjunction2 takes place. If Sun-Moon conjoin in Pisces, for example, it starts Chaitra maasa. These names come from the constellation that Moon is most likely to occupy on the full Moon day. In the month that starts when Sun and Moon conjoin in Pisces, Moon is likely to be in Chitra constellation (23°20' in Virgo to 6°40' in Libra) on the full Moon day (15th tithi – Pournimasya). So the month is called Chaitra. One is called “Nija” Jeshtha maasa and the other is called “Adhika” Jyeshtha maasa. Nija means real and adhika means extra. An adhika maasa (extra month) comes once in every 3 years and that synchronizes the lunar years with solar years. This calendar has been in use in India for millennia.

Rasi of Sun-Moon conjunction that starts the month Name of the month Most likely onstellation  of Full Moon Approx when?
Pisces Chaitra Chitra Mar/Apr
Aries Vaisaakha Visaakha Apr/May
Taurus Jyeshtha Jyeshtha May/June
Gemini Aashaadha Poorva/Uttara Aashaadha June/July
Cancer Sraavana Sravana July/Aug
Leo Bhaadrapada Poorva/Uttara Bhadrapada Aug/Sept
Virgo Aaswayuja Aswini Sept/Oct
Libra Kaarteeka Krittika Oct/Nov
Scorpio Maargasira Mrigasira Nov/Dec
Sagittarius Pushya Pushyami Dec/Jan
Capricorn Maagha Makha Jan/Feb
Aquarius Phaalguna Poorva/Uttara Phalguni Feb/Mar