As the Sun lies over the equator, nearly every part of the world receives an almost equal amount of sunlight, making day and night nearly equal in length, according to an interesting research report.
LAHORE, (UrduPoint / Pakistan Point News – 17th Sep, 2026) Day and night will be equal in duration—12 hours each—in most parts of the world, including Pakistan, between September 21 and 23. This occurs during the autumnal equinox, when the Sun is positioned over the equator, allowing nearly equal amounts of sunlight to reach most parts of the world.
A similar phenomenon occurs in March with the beginning of the vernal equinox.
According to an astronomical journal, autumn begins in the Northern Hemisphere and spring begins in the Southern Hemisphere between September 21 and 24 every year.
Although the duration of autumn has shortened in recent years, the autumnal equinox still begins between September 21 and 24 each year. At this time, the Sun passes over the equator while moving from the Northern Hemisphere toward the Southern Hemisphere, resulting in day and night lasting approximately 12 hours each in most parts of the world, including Pakistan.
The equator is an imaginary line drawn across the exact middle of the world map, dividing the Earth into two equal parts, north and south.
During the autumnal equinox, the Sun rises exactly in the east and sets exactly in the west, making it an important astronomical event. Before the autumnal equinox, the Sun rises in the northeast, while after the equinox it rises in the southeast.
The Earth is tilted to one side as it revolves around the Sun, causing varying amounts of sunlight and heat to reach the planet directly at different times of the year.
During the autumnal equinox, the Sun is over the equator, so nearly every part of the world receives an equal amount of sunlight and day and night are nearly equal in length—approximately 12 hours each.
The same occurs in March, when the vernal equinox begins and the Sun passes over the equator while moving northward.
The Tropic of Cancer period begins in June, while the Tropic of Capricorn period begins in December. The Tropic of Cancer marks the longest day of the year, after which daylight begins to decrease, while the Tropic of Capricorn marks the shortest day, after which daylight begins to increase.
Day and night become equal in March and September, although this does not occur in exactly the same way in some regions.
The word “equinox” means equal night. In ancient times, seasons were determined by the vernal equinox, autumnal equinox, Tropic of Cancer and Tropic of Capricorn.
This year, the autumnal equinox will begin on September 23. After that, daylight will decrease and nighttime will increase in the Northern Hemisphere, while the opposite will occur in the Southern Hemisphere.
