The ancient Indians employed four methods to calculate the duration of a year: 'Nakshatra,' 'Savana,' 'Lunar,' and 'Saura.' Saura was one tropical zodiac-based technique for defining the seasons: equinoxes, solstices, year half, and months in connection to the (six) seasons. Saura calculates the length of a year to be exactly 365 days, 6 hours, 12 minutes, and 30 seconds.