What are Equinoxes and Solstices?
Equinoxes and solstices are frequently used as anchor points for calendars. For people in the northern hemisphere: • Winter solstice is the time in December when the sun reaches its southernmost latitude. At this time we have the shortest day. The date is near 21 December. • Summer solstice is the time in June when the sun reaches its northernmost latitude. At this time we have the longest day. The date is near 21 June. • Vernal equinox is the time in March when the sun passes the equator moving from the southern to the northern hemisphere. Day and night have approximately the same length. The date is near 20 March. • Autumnal equinox is the time in September when the sun passes the equator moving from the northern to the southern hemisphere. Day and night have approximately the same length. The date is near 22 September. For people in the southern hemisphere these events are shifted half a year. The astronomical “tropical year” is frequently defined as the time between, say, two verna
