Linked from
The 29 pages that link to Equinox, each with the reason it gives.
EclipticBroader topic: The ecliptic intersects the celestial equator at the equinoxes.
SeasonsBroader topic: Equinoxes fall between the seasonal daylight extremes marked by solstices.
Earth's axial tiltBroader topic: At an equinox, neither hemisphere is tilted toward the Sun.
SunsetBroader topic: Around an equinox, the Sun sets close to due west across much of Earth.
Solar yearBroader topic: The vernal equinox is a reference point for measuring the seasonal cycle.