When the sun sets on April 20, Muslims around the world will look skyward for a crescent of pale white light—the conclusion to the Islamic holy month of Ramadan emblazoned in the night sky.

Beginning and ending with the new moon, Ramadan falls on the ninth month of the Arabic lunar calendar. It is believed by Muslims to be when the first verses of the Koran were revealed to the Prophet Muhammad more than a millennium ago. From sunrise to sunset, Muslims abstain from food, drink, and vices like gossip and lying. Not only is it meant to be a period of self-reflection, but to serve as a reminder to be charitable to the less fortunate.

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