The two positions that represent an equinox are position B and position D. Equinoxes occur when the Sun is directly above the Earth's equator, resulting in equal lengths of day and night. In position B, the tilt of the Earth's axis is such that the Sun is directly over the equator, indicating the March equinox. In position D, the tilt of the Earth's axis is again such that the Sun is directly over the equator, indicating the September equinox.
