Hindu Calendar 4 of 5

 Different Kinds of Months

The periodic movement of the Moon generates the month / Maas.

The lunar motion is complex, and more so, when it is considered with the motions of the Sun and the Earth, hence, there are many different possible definitions of the month. The length of the month is different for all. These months are

• Synodic
• Sidereal
• Anomalistic
• Draconic/ Nodal
• Tropical

 The Panchang considers the length of all the different months for various purposes, such as calculating tithi, Adhik Maas, the position of nodes (Rahu and Ketu), Eclipses, type duration, location, etc. A synodic month is used for general purposes in Panchang. It considers a mean length of 29.53 days. The actual time between lunations may range from about 29.27 to about 29.83 days.

The beginning of a solar month, Solar Sankranti has many variants (as explained in the previous blog).

So when does a Lunar month begin? Two systems are being followed (this is observed right from the Vedic days). The two systems are known as

Amanta In this system, the lunar month is counted from New Moon to New Moon.

Purnimanta In this system, the month is counted from full Moon to full Moon.

Both systems were prevalent during the Vedic period.

Simple, as compared to conventions on solar month.

The waxing phase of the moon is called " शुक्ल पक्ष, and the waning phase is called कृष्ण पक्ष, in both types of the month 

Naming of the months

In ancient times, the months were named according to the prevailing season. Later, these were rechristened nakshatra names to correspond with the same seasons.

 Ancient Vedic name         Modern name

1. Madhu                            Chaitra
2.  Madhava                       Vaisakha
3. Sukra                               Jyeshtha
4.  Suchi                              Ashadha
5. Nabhas                           Sravana
6. Nabhasya                       Bhadrapada
7. Isha                                 Asvina
8. Urja                                 Karttika
9. Sahas                              Margasirsha
10.  Sahasya                         Pausha
11. Tapas                              Magha
12. Tapasya                          Phalguna

Madhu is "honey", "sweet spring". Madhava. "The sweet one". Sukra and Suchi both mean "bright". Nabhas, the rainy season. Nabhasya, "vapory", "rainy", ish or isha, 'draught" or "refreshment", "fertile". Urja, "strength", "vigour". Sahas strength". Sahasya means "strong". Tapas  , "mortification", "pain", "fire". Tapasya, "produced by heat", "sadhana ". All are Vedic words.

This goes to show that during Vedic times, the year accounting was tropical, ie, season-based.

The sidereal name "Chaitra” came into use about 2000 BCE.

The Sidereal names were derived from the nakshatras. The full-moon tithi (Purnima), on which the moon becomes full when near the nakshatra Chitra, was called Chaitra; the lunar month that contained the Chaitra Purnima was called Chaitra, and so on. See the diagram. The observer is at the centre of the circle. When he sees the full moon in the Chitra Nakshatra, the sun is near the equinox, or the start point of the zodiac, which is also called the beginning of the year. This is how the months got their names. It is easier to observe the position of the full moon than the sun.

However, the full moon does not occur in the same nakshatra every year. Hence, a group of nakshatras was allotted to each month for naming.

Names of lunar months, based on, grouping, of the nakshatra.

Grouping of Nakshatra                               Modern Month Names

• चित्रा ,स्वाति                                                        चैत्र
• विशाखा अनुराधा                                                वैशाख
•  ज्येष्ठा ,मूल                                                          ज्येष्ठ 
• पूर्व आषाढा,  उत्तर आषाढा                                आषाढ  
•  श्रवण ,धनिष्ठा                                                       श्रावण 
• शततारका , पूर्व भाद्रपदा/ उत्तर भाद्रपदा/         भाद्रपद
•  रेवती, अश्विनी,  भरणी                                         अश्विन
• कृत्तिका , रोहिणी                                                 कार्तिक
• मृगशिर, आर्द्रा                                                      मृगशीर्ष
• पुनर्वसु, पुष्य                                                         पौष
• पुष्य , मघा                                                            माघ 
  
• पूर्व फाल्गुनी ,उत्तर फाल्गुनी, हस्त                      फाल्गुन 

By about 1400 BCE, and the introduction of the Rashi system the solar Sankranti was used to denote Lunar months in which the full moon occurred. Most names remained the same. However, some solar calendars changed their names to Rashi's names.

The first month of the year depended upon the type of zodiac used; hence Vaishakh was the first month for the solar year, and Chaitra was the first month for the Lunar year. So, those who follow the solar year start their year from the month of Vaishakh, and those who follow the lunisolar year start the year from the Chaitra month.

The general rule of naming the lunar months to correspond with the solar year is that the amanta month in which the Mesh Sankranti or entrance of the sun into the zodiac sign Mesh, or Aries, occurs in each year is to be called Chaitra, and so on in succession.

The names of the month prevalent today in various parts of India are given in the table

Corresponding Names of Solar Months in Different Places
First Month of the Year is in Capitals
Sun Sankranti	BENGAL/ ODISHA	ASSAM	TAMIL NADU	KERALA
MESH	BAISAKH	BAHAG	CHITTIRAI	MEDAM
VRISHABH	Jyestha	Jeth	Vaikasi	Edavam
MITHUN	Ashadh	Ahar	Ani	Midhunam
KARAK	Shravan	Seon	Adi	Karkitakam
SIMHA	Bhadra	Bhad	Avani	CHINGAM
KANYA	Ashwin	Ahin	Puratassi	KANNI
TULA	Kartika	Kati	Aippasi	Thulam
VRISHIK	Agrayahana	Aghon	Kartikai	Vrischikam
DHANU	Pausha	Poha	Margalj	Dhanu
MARAK	Magha	Magh	Tai	Makaram
KUMBH	Phalgun	Phagun	Masi	Kumbham
MEEN	Chaitra	Chait	Panguni	Meenam

क्षय तिथि and अधिक तिथि 

Tithi, its definition, and accounting as current tithi are explained in Hindu Calendar 2 of 3 and Hindu Calendar 3 of 4

क्षय तिथि

To continue with the same example (as given in part 3), if the sunrise is at 0623 h on 10 January and the चतुर्थी  तिथि finishes at 0947 h, then the tithi for 10 January is चतुर्थी तिथि.

 If the Panchami tithi ends after sunrise (0634 h) on 11 January, then it will be Panchami tithi.

However, if पंचमी तिथि finishes before sunrise on 11 January, say by 0620 h, then  षष्ठी तिथि will be current at sunrise on 11 January. So tithi for 11 January will be षष्ठीतिथि. There will be no पंचमी तिथि, as पंचमी तिथि has lapsed and is not counted.

In short, a tithi on which the Sun does not rise is expunged! That is kshya क्षय तिथि. 

अधिक तिथि 

In the same example above, if the Panchami tithi finishes after sunrise on 11 January, say at 0821 h, and on 12 January, it finishes at 0700 h, then 12 January will still be Panchami, as per the current tithi rule. 

In short, on a तिथि on which the Sun rises twice, the तिथि is repeated. This is अधिक तिथि.

Generally, there are thirteen क्षय तिथि and seven अधिक तिथि in twelve lunar months.

The day on which no tithi ends or a तिथि is repeated is regarded as inauspicious.

  अधिक मासand क्षय मास

The aspect of अधिक मास and  क्षय  मास is peculiar to Luni solar calendars. The process of intercalary month adjustment is to synchronise with the solar calendar and seasons. A lunar year has 354 days, and a solar year has 365 days, a difference of 11 days in a year. Hence, in about 30 months, one month is added as an intercalary month to synchronise. 

अधिक मास

The length of a solar month                                           Length of a Lunar Month

Maximum    31 d 15 h 28 m                                          29 d 19 h 30 m

Minimum     29 d 7 h 38 m                                            29 d 7 h 20 m

When the length of the Solar month is greater than the lunar month, then, in this condition, a second Lunar month starts in the same solar month. or the lunar month completes between two sankrantis. Then this is अधिक मास.

Simply put, the lunar month where there is no transition of the Sun from one rashi to another is अधिक मास. 

Click on the link to see अधिक मास animation. Adhik Maas

क्षय मास

When the length of the Lunar month is greater than the solar month and in the lunar month, where there are two sankrantis/ transistions of the Sun in two rashis, then that month is क्षय मास. This occurrence is not so frequent.

Click on the link to see क्षय मास animation.  Kshay Maas

The adhik and kshya maas and its insertion, for synchronisation, is done on a real-time basis, unlike in the Gregorian calendar, where  1 day is added in February only.

Naming of Adhik/ Kshay Maas

 The insertion of an additional / expunged month has to be at a proper location and named correctly for identification without affecting the time of religious rites, seasons, etc.

Different rules were framed by various teachers. This resulted in variance in practice and caused confusion.

काल तत्व विवेचन - It is a treatise on the rules for the naming of months and times, seasons suitable for the performance of religious rites, and is attributed to sage Vyasa. 

The celebrated astronomer Bhaskaryacharys (1150 CE) used these rules, which were further modified by 1600 CE and are still used today.

Click on the link to see the naming of  अधिक मासand क्षय मास Month names in two systems

Brahma Siddhant and Surya Siddhant give out the detailed process of naming the intercalary months for both Amanta and Poornimanta systems.

The lunar month in which no Sankranti occurs is called Adhik, but the month in which the Sankranti actually occurs is called Nija, which means true or regular month. Examples: Adhik Shravan and Nij Shravan.

See the link Naming

Some Interesting Pecularities.

• During the Vedang period, the intercalary months, primarily adhik maas, were determined based on the mean motions of the sun and moon; hence, no kshay or decayed month could occur.
• However, around 1100 CE, the apparent motions of the new-moon-ending lunar month and the different solar months, as obtained from Siddhantic rules, were used. By these calculations, a क्षय मासoccurred.
• In a 19-year cycle, intercalations generally occur in 3,5,8,11,14,16, and 19th years
• A month becomes intercalary at an interval of 19 years and afterwards gives way to the month preceeding it , rarely to the following one.
• From 300 CE to 1900 CE    मृगशीर्ष , पौष  and माघ were never intercalary.
• The last kshaya mas was माघ in 1983 CE, and the next will be in पौश 2124 CE.
• Poornimanta has a slightly different system of intercalation of the naming of months.

Date Format 

Gregorian calendar 

Today, the date can be written in various formats, such as 

• DD/MM/YYYY, 
• YYYY/MM/DD, 
• MM/DD/YY 

and many more combinations of D, M and Y.

Hindu calendar

The format is 

•  Month / Paksh / Tithi/Samvatsar/ Year of era (Saka, Vikram Samvat, Kollam, Bengal San, etc). 
• Year of Era/ Samvatsar/Month/ Paksha/Tithi. (This format was found in most of the inscriptions found in excavations)

Month Paksh tithi - पौष शुक्ल अष्टमी ( bright half) माघ  कृष्ण अष्टमी (dark half )

A date mentioned in ancient texts is 

 Shalivahan Saka 1602 Raudra SamvatSar Chitra Shuddha Purnima.

                  Era/ Year/Samvatsar Name/Month/Tithi

This date corresponds to the Gregorian calendar-27 March 1680 CE (Full Moon day)

The Gregorian date of 14 March 2025 CE corresponds to 

Saka 1946 Krodhi Phalgun Shukla Poornima

Vikram Samvat 2081 Pingla Phalgun Shukla Poornima 

......................................................... The next blog is on Eras and various dates 

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References:-

1.  Bhartiya Jyotish Shastra-SB Dixit
2. The Indian Calendar-Robert Sewell and SB Dixit
3. Cowasjee Patells Chronology
4. The book of Eras- Gen A Cunningham
5. Calendar Reforms Committee Report 
6. Ancient Indian Astronomy -RN Iyengar
7. The Calendars of India- VK Mishra
8. Video credits from " Vedic Astrology through Animations"