Autumn’s Arrival
September 23—Autumnal Equinox
Fall begins at 5:05 A.M. EDT. The autumnal equinox is defined as the point at which the Sun appears to cross the celestial equator from north to south. The word equinox means “equal night”: Night and day are about the same length of time. In addition to the equal hours of daylight and darkness, the equinox is a time when the Sun’s apparent motion undergoes the most rapid change. Around the time of the equinox, variations in the position on the horizon where the Sun rises and sets can be noticed by alert observers from one day to the next.
Fall begins at 5:05 A.M. EDT. The autumnal equinox is defined as the point at which the Sun appears to cross the celestial equator from north to south. The word equinox means “equal night”: Night and day are about the same length of time. In addition to the equal hours of daylight and darkness, the equinox is a time when the Sun’s apparent motion undergoes the most rapid change. Around the time of the equinox, variations in the position on the horizon where the Sun rises and sets can be noticed by alert observers from one day to the next.
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