Nanakshahi calendar designed by Pal Singh Purewal to replace the Bikrami calendar. The epoch of this calendar is the birth of the first Sikh Guru, Nanak Dev in 1469 and the Nanakshahi year commences on 1 Chet. New Year's Day falls annually on what is March 14 in the Gregorian Western calendar. The start of each month is fixed. According to Kapel (2006), the solar accuracy of the Nanakshahi calendar is linked to the Gregorian civil calendar. This is because the Nanaskhahi calendar uses the tropical year instead of using the sidereal year which is used in the Bikrami calendar or the
Lunar calendar to produce a lunisolar calendar. A 49-month cycle was proposed as the basis of an alternative Easter computation by Isaac Newton around 1700. The tabular Islamic calendar's 360-month cycle is equivalent to 24×15 months, minus a correction of one day. Lunar calendar A lunar calendar is a calendar based upon the monthly cycles of the Moon's phases (synodic months), in contrast to solar calendars, whose annual cycles are based only directly upon the solar year. The most commonly used calendar, the Gregorian calendar, is a solar calendar system that originally evolved out of a lunar calendar system. A purely lunar