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).