Are day and night equal on the equinox? Not exactly
Are day and night equal at an equinox? No. Earth's atmosphere and our sun team up to give us more day than night during an equinox. The post Are day and night equal on the equinox? Not exactly first appeared on EarthSky .
At the September equinox, day and night are not precisely equal, contrary to popular belief. The 2026 equinox will occur at 00:05 UTC on September 23, 2026, marking the Northern Hemisphere’s autumn equinox and Southern Hemisphere’s spring equinox. Two factors contribute to the unequal daylight and darkness: the sun’s size and atmospheric refraction.
Unlike stars, the sun is a disk rather than a point, and sunrise and sunset are defined by the edge of the sun touching the horizon, providing an extra 2.5 to 3 minutes of daylight at mid-temperate latitudes. Additionally, Earth's atmosphere acts like a lens, lifting the sun about 0.5 degrees when it nears the horizon, advancing sunrise and delaying sunset. Consequently, there are approximately six extra minutes of daylight at mid-temperate latitudes.
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