Our planet’s tilt dictates cycle of summer and winter


The seasons are marked by solstices and equinoxes — astronomical terms that relate to Earth’s tilt. The solstices mark the points at which the poles are tilted at their maximum toward or away from the sun. This is when the difference between the daylight hours and the nighttime hours is most acute. The solstices occur each year on June 20 or 21 and Dec. 21 or 22.

Seasons_1This year’s June solstice occurs at 2:46 a.m. ET Tuesday, marking the official start of summer in the Northern Hemisphere and the start of winter in the Southern Hemisphere.

More here.