Why We Have Seasons

The seasons occur because as Earth revolves around the Sun, its axis remains tilted at 23.5 degrees from the perpendicular. This tilt causes different latitudes on Earth to receive varying amounts of sunlight throughout the year.

In the Northern Hemisphere, the summer solstice marks the beginning of summer and occurs when the North Pole is tilted toward the Sun. The winter solstice marks the beginning of winter and occurs when the North Pole is tilted away from the Sun.

The equinoxes occur when the hemispheres equally face the Sun. At this time, the Sun rises due east and sets due west. The vernal equinox marks the beginning of spring; the autumnal equinox marks the beginning of autumn.

In the Southern Hemisphere, the seasons are the reverse of those in the Northern Hemisphere.

THE FIRST DAYS OF THE 2021 SEASONS

VERNAL (SPRING) EQUINOX: March 20, 5:37 a.m. EDT

SUMMER SOLSTICE: June 20, 11:32 p.m. EDT

AUTUMNAL (FALL) EQUINOX: Sept. 22, 3:21 p.m. EDT

WINTER SOLSTICE: Dec. 21, 10:59 a.m. EST