Measurement of time begins July 16
622 AD . when the Prophet Muhammad moved
from Mecca to Medina (Hijra
=arabic, emigration or escape). Originally,
the difference between the Muslim and the Western calendar
was 622 years, but it has now fallen to around 579 since
an Islamic year is shorter. 2011 AD is 1432 AH (anno
The Islamic calendar (it
is known also as Muslim calendar or Hijri
calendar) is a lunar calendar based on 12 lunar months
in a year of 354 or 355 days, used to date events in many
Muslim countries (together with the Gregorian calendar),
and used by Muslims as guidance to celebrate their holy
days and festivals.
Its first year was the year during
which the Hijra, i.e. the emigration of the Islamic
prophet Muhammad from Mecca to Medina,
occurred. Each numbered year is designated either H or
AH. A limited number of years before Hijra (BH) are used
to date events related to Islam, such as the birth of
Muhammad in 53 BH.
or Islamic lunar year is between
10 and 12 days shorter than a Gregorian year.
Though they share 12 lunar
cycles—months—per solar year, the Hijri
calendar uses actual moon phases to mark them, whereas
the Gregorian calendar adjusts
its nearly lunar months to synchronize with the sun.
For religious purposes
months are defined to start with the first observation
of the crescent of the new Moon.