The “polar night” surrounds the winter solstice, when the sun remains below the horizon during the weeks leading up to and following the event.Įvery planet in our solar system experiences solstices. “Midnight sun” describes the phenomenon surrounding the summer solstice, when the sun remains visible at midnight in the weeks leading up to and following the event. In this way, solstices are the extreme examples of “ midnight sun” and “ polar night.” At the North Pole and South Pole, the solstices mark the time when the sun is highest or lowest in the sky. The subsolar point never reaches Arctic and Antarctic regions. The subsolar point will cross every latitude between these extremes twice every year. The subsolar point then begins its migration south, and vertical rays strike the Tropic of Capricorn, 23.5° south of the Equator, during the December solstice. The sun’s vertical rays strike the Tropic of Cancer, 23.5° north of the Equator, during the June solstice. The solstices mark when the subsolar point reaches its northernmost and southernmost latitudes. The subsolar point appears at the Equator twice a year (during the equinoxes), and migrates north and south across the tropics during the rest of the year. It is where the sun appears directly overhead at noon. The subsolar point describes the latitude where the sun’s rays hit Earth exactly perpendicular to Earth’s surface. The Equator, at 0° latitude, receives a maximum intensity of the sun’s rays all year.Īs a result, areas near Earth’s Equator experience relatively constant sunlight and little solstice variation.Įarth’s solstices are largely marked by the transition of the subsolar point across the tropics. At the poles, a solstice is the peak of a radical exposure to daylight, while at the Equator, the solstices are barely marked at all. The December solstice is the winter solstice in the Northern Hemisphere and the summer solstice in the Southern.Įarth’s latitudes experience the solstices in different ways. The June solstice is the summer solstice in the Northern Hemisphere and the winter solstice in the Southern Hemisphere. The winter solstice is the shortest day of the year and has the fewest hours of daylight.
The summer solstice is the longest day of the year, meaning it experiences the maximum intensity of the sun’s rays and has the most hours of sunlight. Sometimes, solstices are nicknamed the “ summer solstice” and the “ winter solstice,” although these have different dates in the Northern and Southern Hemispheres. During an equinox, solar declination is 0°-the Equator-and both the Northern and Southern Hemisphere receive equal sunlight.) (The only times of the year when the intensity of the sun’s rays is not unequal are the appropriately named equinoxes. Throughout the year, this means that either the Northern or Southern Hemisphere is tilted toward the sun and receives the maximum intensity of the sun’s rays. Solstices and shifting solar declinations are a result of Earth’s 23.5° axial tilt as it orbits the sun. During the December solstice (marked between December 20 and December 23), solar declination is about 23.5°S (the Tropic of Capricorn). During the June solstice (marked between June 20 and June 22), solar declination is about 23.5°N (the Tropic of Cancer).
On Earth, solstices are twice-yearly phenomena in which solar declination reaches the Tropic of Cancer in the north and the Tropic of Capricorn in the south.
On our planet, solstices are defined by solar declination-the latitude of Earth where the sun is directly overhead at noon. A solstice is an event in which a planet’s poles are most extremely inclined toward or away from the star it orbits.
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