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Doha, Qatar: The Qatar Calendar House announced today, September 22, that the sun will be perpendicular to the equator tomorrow, September 23, where the phenomenon of the autumnal equinox will occur in the northern hemisphere, while the situation will be opposite in the southern hemisphere, where the phenomenon of the spring equinox will occur.
Dr Bashir Marzouk, astronomer at the Qatar Calendar House, said that on this day, the length of the day and the night in Qatar will be approximately equal, as the length of the day will be 12 hours and 7 minutes, while the length of the night will be 11 hours and 53 minutes, noting that the sun will rise tomorrow, Saturday, at 5:23 am, and will set at 5:30 pm.
Dr. Marzouk added: “The length of the fall semester this year will be approximately 89 days, while the length of the summer semester this year will be approximately 93 days.”
The phenomenon is considered important as autumn equinox (and all four astronomical seasons) is an indicator for climatic changes. In addition, on this day, the directions of east and west can be determined with extreme accuracy at the time of sunrise and sunset, respectively, knowing that the sun on this day will rise and set from the exact positions over eastern and western horizons.
It is worth noting that the four astronomical seasons (winter, spring, summer, and fall) occur as a result of the Earth’s rotation in its orbit around the sun, in addition to the tilt of the Earth’s axis to the plane of its orbit at an angle of 23.5 degrees.
On the day of an equinox, daytime and nighttime are of approximately equal duration all over the world, as they are not exactly equal due to the angular size of the Sun and atmospheric refraction.
