Equinoxes and Solstices

Equinoxes and solstices are key points in Earth's orbit that mark changing seasons. Equinoxes happen twice a year when Earth's tilt is such that day and night are nearly equal, around March 21 (Spring) and September 23 (Autumn). Solstices also occur twice a year: the Summer Solstice around June 21, when the North or South Hemisphere is tilted most toward the Sun, resulting in the longest day; and the Winter Solstice around December 21, when it is tilted away, producing the shortest day. These events are caused by Earth's axial tilt and orbital position, shaping seasonal patterns.