This is due to the fact that the Islamic Hijri calendar is based on lunar cycles, while the Gregorian calendar marks the Earth’s passage around the sun.
The disparity between the two calendars means that Ramadan will fall twice in one Gregorian year roughly every 30 years, the astronomer said in a video posted on his Twitter account.
The last time it happened was in 1997, and before that in 1965. It is due to happen again in 2063.
In the Hijri year 1451 AH, Ramadan will begin around January 5, 2030, and in the year 1452 AH it will fall around December 26, 2030.
This will result in Muslims fasting for around 36 days total in 2030: The full month of 30 days for the year 1451 AH and around six days for the year 1452.
The Hijri lunar year lasts 354 or 355 days, meaning that it does not line up precisely with the Gregorian calendar of 365 days.
This also means that Ramadan falls in different seasons every year – going in cycles of around 32 years.
Ramadan 1449 AH, due to begin in 2028, will take place in midwinter.
In 1466 AH, corresponding to 2044, the holy month is due to begin during the height of summer.
Fasting during Ramadan is observed from sunrise to sunset, meaning that the longest periods of fasting will take place when Ramadan is in the summer, and the shortest when it falls in winter.
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