Hindu Calander

When a new moon occurs before sunrise on a day, that day is said to be the first day of the lunar month. So it is evident that the end of the lunar month will coincide with a new moon. A lunar month has 29 or 30 days (according to the movement of the moon).

When a new moon occurs before sunrise on a day, that day is said to be the first day of the lunar month. So it is evident that the end of the lunar month will coincide with a new moon. A lunar month has 29 or 30 days (according to the movement of the moon).

Sometimes two successive days have the same tithi. In such a case, the latter is called an adhika tithi where adhika means "extra". Sometimes, one tithi may never touch a sunrise, and hence no day will be labeled by that tithi. It is then said to be a tithi kshaya where kshaya means "loss".

Month names

There are twelve months in Hindu lunar Calendar:

1. Chaitra (चैत्र, चैत)
2. Vaishākh (वैशाख, बैसाख)
3. Jyaishtha (ज्येष्ठ, जेठ)
4. Āshādha (आषाढ, आषाढ़)
5. Shrāvana (श्रावण, सावन)
6. Bhaadra or, Bhādrapad (भाद्रपद, भादो)
7. Āshwin (आश्विन)
8. Kārtik (कार्तिक)
9. Agrahayana or, Mārgashīrsha (मार्गशीर्ष, अगहन)
10. Paush (पौष)
11. Māgh (माघ)
12. Phālgun(फाल्गुन)

Determining which name a lunar month takes is somewhat indirect. It is based on the rāshi (Zodiac sign) into which the sun transits within a lunar month, i.e. before the new moon ending the month

There are twelve rāshi names, there are twelve lunar month names. When the sun transits into the Mesha rāshi in a lunar month, then the name of the lunar month is Chaitra. When the sun transits into Vrishabha, then the lunar month is Vaishākh. So on.

If the transits of the Sun through various constellations of the zodiac (Rashi) are used, then we get Solar months, which do not shift with reference to the Gregorian calendar. The Solar months along with the corresponding Hindu seasons and Gregorian months are:

The Sanskrit grammatical derivation of the lunar month names Chaitra etc., is: the (lunar) month which has its central full moon occurring at or near the nakshatra Chitrā is called Chaitra. Similarly, for the nakshatras Vishākhā, Jyeshthā, (Pūrva) Ashādhā, Shravan, Bhādrapad, Ashvinī (old name Ashvayuj), Krittikā, Mrigashīrsha, Pushya, Meghā and (Pūrva/Uttara) Phalgunī the names Vaishākh etc. are derived.

The lunar months are split into two pakshas of 15 days. The waxing paksha is called shukla paksha, light half, and the waning paksha the krishna paksha, dark half.

There are two different systems for making the lunar calendar:

• amavasyanta or mukhya mana system - a month begins with a new moon, mostly followed in the southern states
• purnimanta or gauna mana system - a month begins with a full moon, followed more in the North.

Extra months

When the sun does not at all transit into any rāshi but simply keeps moving within a rāshi in a lunar month (i.e. before a new moon), then that lunar month will be named according to the first upcoming transit. It will also take the epithet of adhik or "extra". For example, if a lunar month elapsed without a solar transit and the next transit is into Mesha, then this month without transit is labeled adhik Chaitra. The next month will be labeled according to its transit as usual and will get the epithet nija ("original") or shuddha ("clean"). [Note that an adhik māsa (month) is the first of two whereas an adhika tithi is the second of two.]

Extra Month, or adhik mas māsa (mas = lunar month) falls every 32.5 months. It is also known as purushottam mas, so as to give it a devotional name. Thus 12 Hindu mas (māsa) is equal to approximate 356 days, while solar year have 365 or 366 (in leap year) which create difference of 9 to 10 days, which is offset every 3rd year. No adhik mas falls during Kartik to Magh.

Extra Month, or adhik mas māsa (mas = lunar month) falls every 32.5 months. It is also known as purushottam mas, so as to give it a devotional name. Thus 12 Hindu mas (māsa) is equal to approximate 356 days, while solar year have 365 or 366 (in leap year) which create difference of 9 to 10 days, which is offset every 3rd year. No adhik mas falls during Kartik to Magh.

A month long fair is celebrated in Machhegaun during adhik māsa. It is general belief that one can wash away all one's sins by taking a bath in the Machhenarayan's pond.

Lost months

If the sun transits into two rāshis within a lunar month, then the month will have to be labeled by both transits and will take the epithet kshay or "loss". There is considered to be a "loss" because in this case, there is only one month labeled by both transits. If the sun had transited into only one raashi in a lunar month as is usual, there would have been two separate months labeled by the two transits in question.

For example, if the sun transits into Mesh and Vrishabh in a lunar month, then it will be called Chaitra-Vaishaakh kshaya. There will be no separate months labeled Chaitra and Vaishākh.

A kshay māsa occurs very rarely. Known gaps between occurrence of kshaya māsas are 19 and 141 years. The last was in 1983. January 15 through February 12 were Pausha-Māgha kshay. February 13 onwards was (adhik) Phālguna.

Special Case:

If there is no solar transit in one lunar month but there are two transits in the next lunar month,

• the first month will be labeled by the first transit of the second month and take the epithet adhik and
• the first month will be labeled by the first transit of the second month and take the epithet adhik and

This is a very very rare occurrence. The last was in 1315. October 8 to November 5 were adhik Kārtik. November 6 to December 5 were Kārtik-Mārgashīrsh kshaya. December 6 onwards was Paush.

Religious observances in case of extra and lost months

Among normal months, adhika months, and kshaya months, the earlier are considered "better" for religious purposes. That means, if a festival should fall on the 10th tithi of the Āshvayuja month (this is called Vijayadashamī) and there are two Āshvayuja months caused by the existence of an adhika Āshvayuja, the first adhika month will not see the festival, and the festival will be observed only in the second nija month. However, if the second month is āshvayuja kshaya then the festival will be observed in the first adhika month itself.

When two months are rolled into one in the case of a kshaya māsa, the festivals of both months will also be rolled into this kshaya māsa. For example, the festival of Mahāshivarātri which is to be observed on the fourteenth tithi of the Māgha krishna paksha was, in 1983, observed on the corresponding tithi of Pausha-Māgha kshaya krishna paksha, since in that year, Pausha and Māgha were rolled into one, as mentioned above. When two months are rolled into one in the case of a kshaya māsa, the festivals of both months will also be rolled into this kshaya māsa.