Neo,
neologist wrote:Tell us more about how this date is calculated
The Islamic (Hijri, Lunar) calendar is based on a lunar month of 29 to 30 days, with the day starting at sunset.
The new moon announces the arrival of a new month, but due to differences in the weather (rain and fog, et cetera) that may prevent a clear view of the moon, or due to great distances between countries, the start of a new month is neither definite nor conclusive. Therefore scientists have developed a number of norms to help predict when the first sighting of the crescent moon will be.
The Islamic year consists of twelve months. The first of these months is called "Muharram". The 10th of Muharram is the day of Ashoora. In other words,
Neo, Ashoora is 1/10 of each Islamic year.
PS: The dating of the Islamic years was introduced by the second caliph, `Umar ibn Al-Khattab, in 638 CE (16 AH) in an attempt to circumvent all the various conflicting dating systems used during his time. After consulting his companions, he set the Hijrah?-the flight of the Prophet (peace and blessings be upon him) from Makkah to Madinah?-as the most appropriate reference to the new Islamic era.
This means that we are now in the lunar year 1427.
And Allah knows best.