You can also think about solstices in terms of where on Earth the sun appears. Likewise, during the Northern Hemisphere's winter solstice-which always falls around December 22-the Southern Hemisphere gets its summer solstice. During the Northern Hemisphere’s summer solstice-which always falls around June 21-the Southern Hemisphere gets its winter solstice. The hemisphere tilted most toward our home star sees its longest day, while the hemisphere tilted away from the sun sees its longest night. On two moments each year-what are called solstices-Earth's axis is tilted most closely toward the sun. The Southern Hemisphere's seasons are reversed. From September to March, the Northern Hemisphere is tilted away, so it feels like autumn and winter. From March to September, the Northern Hemisphere is tilted more toward the sun, driving its spring and summer. This tilt drives our planet's seasons, as the Northern and Southern Hemispheres get unequal amounts of sunlight over the course of a year. Solstices occur because Earth’s axis of rotation is tilted about 23.4 degrees relative to Earth's orbit around the sun. ( Here's the difference between astronomical and meteorological seasons.) What are solstices? So what exactly are solstices-and how have they been celebrated throughout history? Here’s all you need to know. However, today’s meteorologists officially use temperature records instead to draw lines between the seasons. Traditionally, summer and winter solstices helped mark the changing of the seasons-along with their counterparts, the spring and autumnal equinoxes. Solstices occur at the same time around the world, but their local times vary with time zones. South of the Equator, this same moment marks the unofficial beginning of winter. This year, the northern summer solstice falls on June 21 at 5:13 a.m.

First day of summer 2021