Seasons

The beginning of the seasons is given, by convention, by the moments when the apparent ecliptic longitude of the Sun takes on certain values. These moments correspond to when the Sun culminates at a maximum or minimum height above the horizon (summer and winter solstice, respectively) and when the lengths of day and night coincide, except for refraction effects (spring and autumn equinoxes).

The following table shows the starting dates of the seasons and their duration for this year (the length of the seasons hardly varies from year to year).

 

Northern hemisphere Date and time Southern hemisphere Duration in days
Winter 21 December  10:21 summer   88.98
Spring 20 March  10:01 autumn 92.74
Summer 20 June  22:42 winter 93.66
Autumn 22 September   20:19 spring 89.86