A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and set "due west". This occurs twice each year, around 20 March and 23 September.
A solstice is the time when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 20–22 and December 20–22. In many countries, the seasons of the year are determined by the solstices and the equinoxes.
Sunrise is the moment when the upper rim of the Sun appears on the horizon in the morning. The term can also refer to the entire process of the solar disk crossing the horizon.
Sunset is the disappearance of the Sun below the horizon of the Earth due to its rotation. As viewed from everywhere on Earth, it is a phenomenon that happens approximately once every 24 hours, except in areas close to the poles. The equinox Sun sets due west at the moment of both the spring and autumn equinoxes. As viewed from the Northern Hemisphere, the Sun sets to the northwest in the spring and summer, and to the southwest in the autumn and winter; these seasons are reversed for the Southern Hemisphere.
Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizon. This morning twilight period will last until sunrise, when direct sunlight outshines the diffused light.
Midsummer is a celebration of the season of summer, taking place on or near the date of the summer solstice in the Northern Hemisphere; the longest day of the year. The name "midsummer" mainly refers to summer solstice festivals of European origin, especially those in the Nordic countries. In these cultures it is traditionally regarded as the middle of summer, with the season beginning on May Day. Although the summer solstice falls on 21 or 22 June in the Northern Hemisphere, it was traditionally reckoned to fall on 23–24 June in much of Europe. This date was Christianized as Saint John's Eve and Saint John's Day. It is usually celebrated with outdoor gatherings that include bonfires and feasting.
Midnight sun, also known as polar day, is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the Sun remains visible at the local midnight. When midnight sun is seen in the Arctic, the Sun appears to move from left to right. In Antarctica, the equivalent apparent motion is from right to left. This occurs at latitudes ranging from approximately 65°44' to exactly 90° north or south, and does not stop exactly at the Arctic Circle or the Antarctic Circle, due to refraction.
Twilight is light produced by sunlight scattering in the upper atmosphere, when the Sun is below the horizon, which illuminates the lower atmosphere and the Earth's surface. The word twilight can also refer to the periods of time when this illumination occurs.
The September equinox is the moment when the Sun appears to cross the celestial equator, heading southward. Because of differences between the calendar year and the tropical year, the September equinox may occur from September 21 to 24.
Nuit Blanche is an annual all-night or night-time arts festival of a city. A Nuit Blanche typically has museums, private and public art galleries, and other cultural institutions open and free of charge, with the centre of the city itself being turned into a de facto art gallery, providing space for art installations, performances, themed social gatherings, and other activities.
The winter solstice, also called the hibernal solstice, occurs when either of Earth's poles reaches its maximum tilt away from the Sun. This happens twice yearly, once in each hemisphere. For that hemisphere, the winter solstice is the day with the shortest period of daylight and longest night of the year, and when the Sun is at its lowest daily maximum elevation in the sky. Each polar region experiences continuous darkness or twilight around its winter solstice. The opposite event is the summer solstice.
Daytime as observed on Earth is the period of the day during which a given location experiences natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. In direct sunlight the movement of the sun can be recorded and observed using a sundial that casts a shadow that slowly moves during the day. Other planets and natural satellites that rotate relative to a luminous primary body, such as a local star, also experience daytime, but this article primarily discusses daytime on Earth.
The Scarlet Sails is a celebration in St. Petersburg, Russia, the most massive and famous public event during the White Nights Festival every summer.
Saint Petersburg has always been known for its high-quality cultural life, and its best known museum is the Hermitage.
Sun path, sometimes also called day arc, refers to the daily and seasonal arc-like path that the Sun appears to follow across the sky as the Earth rotates and orbits the Sun. The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season.
The 72nd parallel north is a circle of latitude that is 72 degrees north of the Earth's equatorial plane, in the Arctic. It crosses the Atlantic Ocean, Europe, Asia, the Arctic Ocean and North America.
A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that reaches the Earth's surface, variations of which may cause animals to undergo hibernation or to migrate, and plants to be dormant. Various cultures define the number and nature of seasons based on regional variations, and as such there are a number of both modern and historical cultures whose number of seasons varies.
The 72nd parallel south is a circle of latitude that is 72 degrees south of the Earth's equatorial plane in the Antarctic. The parallel passes through the Southern Ocean and Antarctica.
The White Nights are all-night arts festivals held in many cities in the summer. The original festival is the White Nights Festival held in Saint Petersburg, Russia. The white nights is the name given in areas of high latitude to the weeks around the summer solstice in June during which sunsets are late, sunrises are early and darkness is never complete. In Saint Petersburg, the Sun does not set until after 10 p.m., and the twilight lasts almost all night.
Saint Petersburg – second-largest city in Russia. An important Russian port on the Baltic Sea, it has the status of a federal subject. Its name was changed to "Petrograd" in 1914, then to "Leningrad" in 1924, and back to Saint Petersburg in 1991.
