Chandramana - a Luni-Solar Calendar

Most of our special days are based on
the moon. So, let us today see the basics
of Chandramana calendar -
the Hindu luni-solar calendar.

We saw in a previous article that
29.5 days constitute a lunar month.

So in a lunar year there are about
354 days (29.5 days x 12 months).

One thing that happens on a yearly
basis are the seasons.
And seasons are independent of
the lunar position / lunar calendar.

Seasons are solely dependent on earth's
movement around the sun.
That is the solar year.
Solar year is about 365 days.

There is a difference of about 11 days
between the solar and lunar years.

So a pure lunar calendar would have its
new year shifted to earlier time with
reference to the season / solar calendar.

Suppose the new year of a pure
lunar calendar is in May of this year.
In ten years time its new year would
be in January.

The Islamic calendar is an example of
a pure lunar calendar. You might have
noticed that Ramzan, the month of fast,
keeps shifting. These days it is during
the rainy season. 8 years later it will
be in mid-summer.

If we were to follow such a calendar,
Rama Navami which is observed
around the beginning of summer can happen
in the middle of winter !

Most cultures wanted their special days
to follow the season.
So, in order to synchronise the lunar
calendar with the seasons, an extra
month is added once in around 33 months.

This is why Chandramana calendar is
called a luni solar calendar.
This calendar is used in some
way or the other across India.

Within the Chandramana tradition
there are two variations on when
a new lunar month starts.

In the traditions south of Narmada,
the new month starts at the next tithi
after Amavasya (new moon).

The new month starts at the tithi after
Purnima (full moon) in the traditions
north of Narmada. [*]

This is the 11th in the
weekly newsletter series.
For past newsletters, see:

[*] As quoted in
Shraadha Kandam of Smriti Mukta Phalam of Vaidyanatha Dikshita pg 162

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