Fasting during the holy month of Ramadan is meant to be a physical and spiritual challenge for Muslims, something that draws them closer to God. But depending on where they are in the world, some followers of the faith might have an especially hard time observing the fast.
During Ramadan, Muslims are encouraged to abstain from food, drink, smoking and sex between the Fajr prayer, which is said at dawn, to the Maghrib prayer, which is said just after sunset. By separating themselves from these physical desires, the fast helps Muslims turn their focus instead towards prayer, introspection and charity.
In the Arabian Peninsula, where Islam got its start in the year 610, daylight doesn't last much longer than 15 hours. But in regions of the world where the sun stays in the sky for a good part of the day, Muslims face tough questions about how long to keep the fast and still stay healthy.
In Reykjavik, Iceland, daylight lasts for about 21 hours and 38 minutes on June 6, which is predicted to be the first full day of Ramadan. In contrast, Muslims in Punta Arenas, Chile, only have to fast for 9 hours and 51 minutes.
In the chart below, HuffPost Religion compared how long daylight lasts in cities around the world on June 6. The differences are remarkable.
Islamic scholars have provided various opinions on how Muslims who live in the far north should observe Ramadan. Some insist on keeping the fast for the entire time, as long as the participants are healthy, able and willing. Others suggest fasting for a more moderate amount of time -- such as 12, 14, or 16 hours. There are others who recommend keeping the fasting times observed at Mecca, or at the 45th parallel north, a circle of latitude that is about halfway between the equator and the North Pole.
In addition, not all Muslims are required to fast during the holy month. People who are sick, elderly, pregnant, menstruating or traveling can make up their fast by observing it on a later date, or agreeing to feed the poor.
Graphic by Alissa Scheller for The Huffington Post.