Tag Archives: calendar

Understanding lunar cycles with the help of Indian Calendar

[Update] This blog was also republished by HBCSE, TIFR‘s Small Science Website: http://smallscience.hbcse.tifr.res.in/lunar-cycles-and-indian-calendars/

Outer Space and celestial bodies are something that fascinates everyone, including children. Many countries invest lot of time and resources in exposing children to space research. Space exploration can also serve as a stimulus for children to enter the fields of science and engineering. How should we begin with at the school level?

At Gyankriti one can notice that children write Gregorian calendar dates in English notebooks and Vikram Samvat dates in Hindi notebooks. The children are also regularly told to go to the terrace and observe the moon. There are two learning objectives associated with this

  1. Understand the phases of moon throughout the year and co-relate it with the hindu calendar. [Subject: Science]
  2. Understand the logic behind ever-changing dates of Hindu festivals. [Subject: General Knowledge]

Sample of dates written in Hindi and English notebooks.

In this blog we have explained the curriculum of Indian Calendar at our school.

About the Indian Calendars

One can find more details about various versions of Indian Calendar and the astronomical concepts behind them on the website of Positional Astronomical Centre of Indian Meterological Department. http://www.packolkata.gov.in They also publish the national calendar of India, Rashtriya Panchang, with the objective of unifying the divergent practices of calendar systems existing in different parts of the country and also to promote panchang calculations on a modern scientific basis.

 As we are using Vikram Samvat at our school, here are some basic details of the luni-solar hindu calendar.

  • The Indian calendar is known by the Hindu word “panchanga“.
  • The calendar is based on the lunar cycle. A day is measured as the period between one moonrise and the next. A month is the period from one moon cycle to the next. A year is measured from the beginning of a season until its return.
  • A lunar month lasts 29.5 days on average.
  • A lunar year lasts 12 lunar months or 354 solar days.

Since a period of twelve lunar months fall short of a solar year by 11 days, an additional month is added to the calendar at three-yearly intervals. This month is known as the “adhika“. Each month is divided into the two cycles (waxing and waning) of the moon (new moon to full moon and back). The period of the new moon is called “krishna paksha” and the period of the full moon is called “shukl paksha“.

One can find more details about various versions of Indian Calendar and the astronomical concepts behind them on the website of Positional Astrononimal Centre of Indian Meterological Department. http://www.packolkata.gov.in

Which calendar should we follow at our school?

The Indian Calendar Reform Committee, appointed in 1952, identified more than thirty well-developed calendars, in use across different parts of India. There are two main calendars. In North India, the month generally begins with the full moon, in South India with the new moon. Festival days will still fall on the same day, or very closely, but the name of the month may be different. For example, Krishna’s Birthday falls on the eighth day of the dark moon; in the North this is in the month of Bhadra; in the South in Shravana.

Well that’s a bit complicated to begin with. Choosing the ‘perfect calendar’ for our school was very confusing. In the end it didn’t really matter which calendar we follow, as our main objective is learning its co-relation with lunar cycles. That is why we decided to go with Vikram Samvat which was started by King Vikramaditya of Ujjain in 57BC, that is 57 years before Gregorian calendar. Vikram Samvat is the most popular version in Madhya Pradesh and hence all the festivals in our region rely on its dates. For finding out the correct tithi everyday we refer the dates published in the local daily Dainik Bhaskar.

So you can use the most popular Indian calendar of your region and pick the dates from any newspaper of your area.

Grade wise learning outcomes related to space exploration

We have introduced Grade1 in this academic session and it is the senior most class at our school. That is why the curriculum outlined here is just an extrapolation of what we have been doing recently. Depending on our experiences the actual content might change over the years.


  • Learn the names of days in a week (Somvaar, Mangalvaar, …)
  • Understand the concept of day and night with the help of globe

Grade1 & Grade 2:

  • Learn names of months in the Indian Calendar.
  • Read the date from school calendar and write in Hindi notebooks everyday.
  • Understand the tithi and paksh
  • Observe the moon regularly at home
  • Co-relate the tithi and paksh of a day with the phase of moon on that night.
  • Learn names of planets in our solar system and their relative position to each other

Grade 3 onwards:

  • Understand the dates of major Indian festivals and link them to the phase of moon [For eg. Krishna Janmasthami falls always on the Krishna Paksha Asthami of Shravan month in Vikram Samvat era]
  • Observe timings of moon-rise and moon-set everday
  • Rotation of Moon around the Earth and Moon-Earth around the Sun. Making working models and relating it with the calendar.
  • Any other astronomical facts related to calendar.

Acknowledgement: Mr. Anand Bhushan, Assistant Professor, NIT Patna, helped us a lot in formulating the curriculum for teaching the Hindu calendars. You can reach him at: anand.bhushan@nitp.ac.in