In case you haven’t already noticed this year the Hindu calendar contains one extra month i.e. 13 instead of regular 12 months.
It is believed that during this period the sun does not transit into any rasi but keeps moving within a rasi of the lunar month.
This is primarily because of a difference of 11 days between the lunar and solar year. The Hindu — lunar calendar, based on the cycles of the Moon has 29.5 days while a solar month has 30-31 days.
The net result is that a lunar year has 354 solar days while the solar year consists of 365 days. As a result at the end of every two or three solar years and extra month-around 29 days- is added to the lunar year to balance the number of days in the two calendars.
Adhika Masa occurs after every 32 months, 16 days and 8 Ghadis. A Ghadi is 24 minutes.
Adhika Masa is also known as purusottama masa and is supposed to be an occasion to wash away one’s sins by taking a bath in a sacred pond. It is dedicated to Lord Krishna.
The Hindu or “Saka calendar” was introduced in 1957.
The day starts with the sunrise according to the Hindu calendar. It has five properties:
Tithi – at sunrise
Vara – name of the weekday for instance: somavara, ravivara
Naksatra in which the moon resides at sunrise
Yoga –alignment. The yoga that is active during sunrise of a day is the prevailing yoga for the day.
Karana (half of a tithi) karana is the time required for the angular distance between the sun and the moon to increase in steps of 6° starting from 0°. The Vedic day begins at sunrise. The karaṇa at sunrise of a particular day shall be the prevailing karana for the whole day.
These 5 limbs or properties form the panchangas.