A solstice is an event in which a planet’s poles are most extremely inclined toward or away from the star it orbits.On our planet, solstices are defined by solar declination—the latitude of the Earth where the sun is directly overhead at noon. 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. During the June solstice (marked between June 20 and June 22), solar declination is about 23.5°N (the Tropic of Cancer). During the December solstice (marked between December 20 and December 23), solar declination is about 23.5°S (the Tropic of Capricorn).Solstices and shifting solar declinations are a result of Earth’s 23.5° axial tilt as it orbits the sun. 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. (The only times of the year when the intensity of the sun’s rays is not unequal are the appropriately named equinoxes. During an equinox, solar declination is 0°—the Equator—and both the Northern and Southern Hemisphere receive equal sunlight.)Sometimes, solstices are nicknamed the “summer solstice” and the “winter solstice,” although these have different dates in the Northern and Southern Hemispheres. 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. The winter solstice is the shortest day of the year and has the fewest hours of daylight.The June solstice is the summer solstice in the Northern Hemisphere and the winter solstice in the Southern Hemisphere. The December solstice is the winter solstice in the Northern Hemisphere and the summer solstice in the Southern.The Science of SolsticesEarth’s latitudes experience the solstices in different ways. 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.Equatorial RegionsThe Equator, at 0° latitude, receives a maximum intensity of the sun’s rays all year.As a result, areas near Earth’s Equator experience relatively constant sunlight and little solstice variation.Mid-latitudesEarth’s solstices are largely marked by the transition of the subsolar point across the tropics. The subsolar point describes the latitude where the sun’s rays hit the Earth exactly perpendicular to the Earth’s surface. It is where the sun appears directly overhead at noon.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. The solstices mark when the subsolar point reaches its northernmost and southernmost latitudes.The sun’s vertical rays strike the Tropic of Cancer, 23.5° north of the Equator, during the June solstice. 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 subsolar point will cross every latitude between these extremes twice every year.Polar RegionsThe subsolar point never reaches Arctic and Antarctic regions. At the North Pole and South Pole, the solstices mark the time when the sun is highest or lowest in the sky. In this way, solstices are the extreme examples of “midnight sun” and “polar night.”“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. The “polar night” surrounds the winter solstice, when the sun remains below the horizon during the weeks leading up to and following the event.Extraterrestrial SolsticesEvery planet in our solar system experiences solstices. The timing and extent of solstices are largely determined by the planet’s axial tilt, orbital eccentricity, and distance from the sun.Venus, the planet closest to Earth, has a very small axial tilt, just 3°. Venus experiences very little seasonal variation, and its solstices are separated by about three months.Mars, our other close neighbor, has an axial tilt similar to Earth (24°). However, Mars has a significantly greater orbital eccentricity, meaning it orbits the sun in a more elliptical shape than Earth. As a result of Mars’ larger orbital eccentricity and axial tilt, the Red Planet experiences extreme seasonal variations and its solstices are about 11 months apart.The Culture of the SolsticesSolstices now mark the beginning of winter and summer, but because some ancient cultures only recognized these two seasons (there was no autumn or spring), the solstices occurred in the middle of the season. Solstices are known as midwinter and midsummer for this reason.Since ancient times, many cultures have marked the solstices with holidays and festivals.MidwinterFollowers of many ancient traditions honored the winter solstice, which signaled the cold, winter season. Winter weather put ancient cultures at their most vulnerable; both food and shelter were limited. Many festivities emphasize light, recognizing the winter solstice as the shortest, darkest day of the year.In many cultures, holidays surrounding midwinter are more prayerful than celebratory—they include cultures praying for survival through the dark and cold, as well as celebrating the spirit of cooperation that helps communities survive difficult times. In other places, midwinter celebrations are the last festivals before the long “famine months” of winter.Monuments to midwinter holidays can be seen at Stonehenge, in Great Britain, and the so-called Intihuatana Stone (the so-called “hitching post of the sun”) at the Incan ruin of Machu Picchu in Peru. At these sites, people gathered to celebrate and pray for their survival through the rest of winter.In Japan, midwinter (toji) is marked by traditional yuzuyu hot citrus baths. Yuzuyu are practical as well as symbolic. The hot tubs filled with dozens of citrus fruit are intended to focus prayers for the new year, as well as warm the body and soothe skin chapped by winter winds.The Sha’lak’o midwinter dance is a custom among the Zuni peoples of the Southwestern United States. During the Sha’lak’o, dancers representing the Zuni fire god and rain god, help the communities bid farewell to the old year and seek blessings in the new.Perhaps the most famous midwinter celebration is the Saturnalia of Ancient Rome. Saturnalia was celebrated the weeks leading up to the actual solstice. Saturnalia was a wild carnival, as well as a time to mark the passing of the seasons. During Saturnalia festivities, Romans enjoyed banquets, gambling, jokes, gifts, and a tradition of usurping strict social structures. At Saturnalia feasts, masters may have served their slaves, and a “King of Saturnalia” could be appointed to manage merrymaking—decreeing that guests must jump in a river or wear outrageous costumes, for instance.Early Christians adopted the timing of Saturnalia for two of their most important seasons, Advent and Christmas. Pagans and neopagans, followers of early European religious traditions, still celebrate the winter solstice as a holiday called Yule.MidsummerMidsummer heralded the height of agricultural fertility and the slow onset of the harvest season. The growing and harvesting of crops, management of domestic animals, and the ability to hunt wild game were all crucial to the survival of ancient cultures. Midsummer festivals are often celebrations of nature’s bounty.Ancient European tribes celebrated midsummer with feasts and bonfires, intended to drive away evil spirits. In Alpine and Germanic regions, summer solstice bonfires are so ingrained in the cultures they have their own name: Sonnwendfeuer. Many of these traditions still survive in Europe and countries that have large populations with European (especially Scandinavian) heritage, such as Canada and the United States.In Finland, midsummer (Juhannus) celebrations include bonfires, saunas, and barbeques. Due to Finland’s proximity to the Arctic, the summer solstice itself can have very little darkness. This makes midsummer in Scandinavia an ideal time for weeklong outdoor music festivals and family vacations.In Ancient Egypt, the summer solstice signaled the beginning of the new year. Sirius, the brightest star in the night sky, appeared soon after the summer solstice. Egyptian astronomers associated the annual appearance of Sirius with the seasonal flooding of the Nile River, which the civilization depended on for agriculture.Due to its association with fertility and abundance, midsummer is often associated with romance and marriage. One of the most famous expressions of this romantic sentiment is the comic play “A Midsummer Night’s Dream,” by the English writer William Shakespeare. In the play, fairies enchant two couples in a magical forest—and haphazardly get enchanted themselves. The play’s many role-reversals and changes in appearance are thematically tied to the solstice.AnalemmaAn analemma is a narrow, figure-8 shaped pattern made by tracking the position of the sun over the course of a year from a fixed time and place. The top and bottom of an analemma mark the solstices.Shifting SolsticesIn any year which is not a leap year, solstices occur about 5 hours and 48 minutes later from one year to the next. This is why the seasons would drift later and later in the year if it was not for an additional day being inserted into every fourth year on February 29.Midwinter in AntarcticaThe June solstice is easily the biggest celebration in Antarctica, marking the day when the sun may begin to appear on the horizon after months of “polar night.” The few scientists who overwinter at the bases in Antarctica celebrate with feasts, shared presents … and an icy polar plunge!St. John's DayOne of the most prevalent solstice celebrations is St. John’s Day, marked in the Christian calendar on the June solstice. St. John’s Day, honored as the birthday of St. John the Baptist, is celebrated with feasts and parties in regions with large Christian populations. Some of the largest festivities of St. John’s Day take place as Festa Junina in Brazil.
Term Part of Speech Definition Encyclopedic Entry abundance Noun
in the Christian calendar, the season beginning four Sundays before Christmas.
having to do with farmers, farming, or their way of life.
having to do with the Alps mountain range.
ancient Rome Noun
civilization founded on the Mediterranean Sea, lasting from the 8th century BCE to about 476 CE.
region at Earth's extreme south, encompassed by the Antarctic Circle.
region at Earth's extreme north, encompassed by the Arctic Circle.
Encyclopedic Entry: Arctic associate Verb
person who studies space and the universe beyond Earth's atmosphere.
axial tilt Noun
angle between an object's axis of rotation and its orbital axis, perpendicular to the orbital plane. Earth's axial tilt is about 23.5 degrees.
large feast, or to eat at a large feasting party.
large outdoor fire.
traveling show with games, performances, and food.
to observe or mark an important event with public and private ceremonies or festivities.
to crack, roughen, and redden the skin.
people and culture focused on the teachings of Jesus and his followers.
Christian holiday celebrating the birth of Jesus of Nazareth.
type of fruit tree, including lemon and orange.
complex way of life that developed as humans began to develop urban settlements.
Encyclopedic Entry: Key Components of Civilization crop Noun
Encyclopedic Entry: crop crucial Adjective
learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.
domestic animal Noun
animal that has been tamed for work or to be a pet.
our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.
Encyclopedic Entry: Earth enchant Verb
to cast a spell on, or subject to magical influence.
period in which daylight and darkness are nearly equal. There are two equinoxes a year.
Encyclopedic Entry: equinox famine Noun
an extreme shortage of food in one area during a long period of time.
to eat large amounts of food, usually to celebrate or honor something.
capacity of soil to sustain plant growth; or the average number of children born to women in a given population.
Encyclopedic Entry: fertility forest Noun
ecosystem filled with trees and underbrush.
wild animals hunted for food.
having to do with randomness, chance, and lack of planning.
the gathering and collection of crops, including both plants and animals.
cultural or family background.
period of celebration or honor.
people and culture native to the Andes Mountains and Pacific coast of South America.
slant, slope, or dip.
to instill, or impress deeply in the mind and consciousness.
distance north or south of the Equator, measured in degrees.
Encyclopedic Entry: latitude magic Noun
control of natural or spiritual forces.
midnight sun Noun
sunlight visible all night at certain times of the year in Arctic and Antarctic regions.
period around the summer solstice, the longest day of the year.
(Dec. 22 in the Northern Hemisphere, June 22 in the Southern Hemisphere) winter solstice.
large structure representing an event, idea, or person.
Northern Hemisphere Noun
half of the Earth between the North Pole and the Equator.
North Pole Noun
fixed point that, along with the South Pole, forms the axis on which the Earth spins.
Encyclopedic Entry: North Pole orbit Verb
to move in a circular pattern around a more massive object.
Encyclopedic Entry: orbit orbital eccentricity Noun
factor by which an astronomical object varies from a perfect circle in its orbit around another body.
following the religious traditions of ancient Europe, including polytheism and nature worship.
at a right angle to something.
phenomena Plural Noun
(singular: phenomenon) any observable occurrence or feature.
large, spherical celestial body that regularly rotates around a star.
Encyclopedic Entry: planet polar night Noun
lack of sunlight at all hours at certain times of the year in Arctic and Antarctic regions.
extreme north or south point of the Earth's axis.
Roman festival around the winter solstice.
room in which steam causes visitors to sweat.
region and name for some countries in Northern Europe: Iceland, Norway, Sweden, Finland, and Denmark.
period of the year distinguished by special climatic conditions.
Encyclopedic Entry: season seasonal flooding Noun
overflowing of a body of water from its banks, usually predicted by yearly rains or storms.
to communicate using signs.
brightest star in Earth's sky, in the constellation Canis Major. Also called the Dog Star.
person who is owned by another person or group of people.
solar declination Noun
angle between the rays of the sun and the plane of the Equator.
astronomical event that occurs twice a year, when the sun appears directly overhead to observers at the Tropic of Cancer or the Tropic of Capricorn.
Encyclopedic Entry: solstice Southern Hemisphere Noun
half of the Earth between the South Pole and the Equator.
South Pole Noun
fixed point that, along with the North Pole, forms the axis on which the Earth spins.
Encyclopedic Entry: South Pole star Noun
large ball of gas and plasma that radiates energy through nuclear fusion, such as the sun.
prehistoric monument in Salisbury Plain, England.
subsolar point Noun
area of a planet where the sun is perceived to be direcly overhead.
time of year when part of the Earth receives the most daylight: The months of June, July, and August in the Northern Hemisphere and the months of December, January, and February in the Southern Hemisphere.
summer solstice Noun
day of the year with the most hours of sunlight, June 20 or 21 in the Northern Hemisphere and December 21 or 22 in the Southern Hemisphere.
star at the center of our solar system.
serving as a representation of something.
beliefs, customs, and cultural characteristics handed down from one generation to the next.
community made of one or several family groups sharing a common culture.
Tropic of Cancer Noun
line of latitude 23.5 degrees north of the Equator.
Tropic of Capricorn Noun
line of latitude 23.5 degrees south of the Equator.
tropics Plural Noun
region generally located between the Tropic of Cancer (23 1/2 degrees north of the Equator) and the Tropic of Capricorn (23 1/2 degrees south of the Equator).
Encyclopedic Entry: tropics usurp Verb
to seize without authority, or turn over an established order.
up-down direction, or at a right angle to Earth and the horizon.
capable of being hurt.
time of year when part of the Earth receives the least daylight: December, January, and February in the Northern Hemisphere and June, July, and August in the Southern Hemisphere.
winter solstice Noun
(December 22 in the Northern Hemisphere, June 22 in the Southern Hemisphere) longest night of the year and the beginning of winter.