How many hours of daylight does the equator experience on September equinox?

On the September equinox, which typically occurs around September 23rd, the Sun's direct rays fall vertically on the equator [2]. The term 'equinox' is derived from the Latin words 'aequus' (equal) and 'nox' (night), signifying that day and night are of equal length across the globe [2][t1]. Specifically, at the equator, there is always approximately 12 hours of sunlight and 12 hours of darkness [c4][t8]. While atmospheric refraction can technically cause the sun to appear slightly before it rises and after it sets—potentially adding a few minutes to the perceived daylight—the standard astronomical and geographical definition for the equinox at the equator is 12 hours of daylight [c3][t1][t3]. This occurs because the Earth's axis is neither tilted towards nor away from the Sun, making the circle of illumination pass through both poles [c1][t10].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Equinox > p. 254
2. [2] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > THE ALTITUDE OF THE MIDDAY SUN > p. 7