during which two months (equinoxes) do all locations on earth experience 12 hours of daylight
Equinox An equinox is commonly regarded as the moment the plane of Earth's equator passes through the center of the Sun's disk,[2] which occurs twice each year, around 20 March and 22-23 September. In other words, it is the point in which the center of the visible sun is directly over the equator. This simplified, but incorrect, understanding of Earth's orbital motion can lead to errors of up to 69 seconds from the actual time of equinox.
Equinox In other words, the equinoxes are the only times when the subsolar point is on the equator, meaning that the Sun is exactly overhead at a point on the equatorial line. The subsolar point crosses the equator moving northward at the March equinox and southward at the September equinox.