Happy new year!

A new year has begun according to the Islamic, or Hijra, calendar. In honor of the holiday, here are some interesting facts about the dating system.

1. The Islamic calendar counts time from what is known in the Gregorian calendar as 622 AD. The current Islamic year is thus 1437 AH.

This year was chosen because it is the year that Mohammed immigrated from Mecca to Medina.

2. However, the calendar was not actually used until 638 AD.

This came about when Abu Musa Ashaari complained to officials of the Calif Umar in Basrah that correspondence lacked dates. After discussing, they decided to start counting the Islamic era from the time of the hijra.

3. There are 354 days in a Hijra year.

On leap years, one day is added to the 12th month, giving it 30 days.

4. Because the Islamic year is shorter than the Gregorian year, it will eventually catch up

Right now, there is a 578 year difference between the Gregorian and Islamic calendars. However, in the year 20,874 AD, it will also be 20,874 AH.

5. The earliest surviving use of the Islamic calendar is on a papyrus from Egypt and is written as 22 AH (643 AD).

The papyrus is known as PERF 558 and also is the oldest surviving Arabic papyrus.