Panchang

Our Hindu calendar is called as Panchang. Panchang is made of two words - ‘Panch' meaning 5 and ‘Ang’ meaning parts. Every day in the Hindu calendar is made of 5 parts and hence the calendar is called Panchang.. Hindu calendars are inherited from a system first defined in Vedāṅga Jyotiṣa's of Lagadha, a late BCE adjunct to the Vedas, standardized in the Sūrya Siddhānta (3rd century CE) and subsequently reformed by astronomers such as Āryabhaṭa (499 CE), Varāhamihira (6th century CE), and Bhāskara II (12th century CE). 

The Hindu calendar is based upon the lunar and solar systems. With the new moon appearing after every 27.1/2 days, the 12 lunar months take 354 days. The difference of 11 days is adjusted every three years when an additional month called adhik-mas is added. A month is divided into 2 parts - Shukla Paksha and Krishna Paksha. The first fortnight between New Moon Day and Full Moon Day is called Shukla Paksha. The period of the brightening moon (waxing moon), and the second fortnight of the month is called Krishna Paksha. 

Each day starts with sunrise and is made of 5 parts - Vara, Tithi, Yoga, Nakshatra and Karana. Vara indicate the day of the week such as ‘ravi- vara’. Tithi, Naksahtra and Yoga indicate the relative path, position and longitude of the moon with respect to the Sun. There are 30 Tithis, 27 Nakshatras and 27 Yogas. Karana is half of a Tithi and there are 60 Karanas.