UAE Islamic holidays explained: Why Ramadan, Eid dates in the country may be different from others

Astronomical calculations and moon sightings do not contradict one another, but are used in tandem when it comes to determining the Islamic calendar, according to an expert.

In a conversation with Khaleej Times, Hasan Hariri, director of the Dubai Astronomy Group, said that the lunar calendar is not specific to the Islamic world nor was it introduced by Islam.

“Many civilisations have historically used the lunar calendar for their month calculations. The sun is a bit difficult because you have to manage it the whole year and there’s no distinguishing boundaries for each month. But with the moon, it’s very clear and obvious that you can create a month with it,” he said. In fact, the Chinese, Egyptians and Mesopotamians all adopted the lunar calendar and used it frequently, he explained.

In Islam, time is seen as a precious, priceless commodity. This is why there was a need to adopt a system that allows for its measurement. Many Islamic actions, explained Hasan, are based on the concept of time. Hajj, the Muslim pilgrimage, can only be done at a specific time of the year by all Muslims around the world. “Think about the five prayers, the annual zakat and of course, Ramadan," he added. "These are all actions that are bound and ruled by time, so it was a necessity."

The lunar calendar is a resilient system because it depends on the moon as a visible celestial body, explained Hasan. But why is it that sometimes the lunar month is 29 days and sometimes 30? According to Hasan, it all has to do with geometry.

“The orbit of the moon is tilted over the equator of the earth, it’s not exactly on the same level as the earth’s equator. That’s why sometimes they are seen clearly and sometimes not clearly because it depends on the geometry between earth, moon and sun. The orbit is also elliptical and not a circle. That’s why the geometry allows us to see the moon early or late,” he explained.

Even though astronomical calculations can in fact determine the presence of the moon, it is an Islamic obligation to ‘sight’ it. He quoted a saying (hadith) by Prophet Muhammad (PBUH) which says, 'Fast when you see the moon, and break fast when you see the moon.'

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