What is a solstice? Definition and explanation:
A solstice, in colloquial terms too solstice called, describes the time at which the sun has the greatest distance to the so-called celestial equator to project the equator into space. The equator refers to the great circle, which lies exactly in the middle between north and south pole, thus has the same distance from both poles and is defined with a geographic latitude of 0 °.
Solstices occur twice a year all over the world and mark the beginning of winter or summer. In our latitudes - ie in the northern hemisphere - the summer solstice usually takes place on June 21st while that time in the southern hemisphere is the beginning of winter. Of the 21st December however, it defines the day of the winter solstice in the northern hemisphere and heralds summer in the southern hemisphere. Solstices, depending on the season, bring the shortest or longest day of the year and, associated with this, the longest or shortest night.
Basics for understanding a solstice
For those times when equinoxes occur on Earth, the two intersections between the celestial equator and the so-called ecliptic are significant. These mark the beginning of spring and autumn. Summer and winter, on the other hand, are defined by the tropics, which are located south and north of the equator. At the tropics, the sun stands at its zenith during a solstice, that is, vertically above it. Even with solstices, which divide the annual cycle into shorter or longer days depending on the position of the sun, the ecliptic thus plays an essential role.
The ecliptic refers to any large circle on the celestial sphere that seems to define the movement of the sun during a year. However, this is only an imaginary circle that actually marks the orbit of our planet around the sun. Since the ecliptic is inclined by 23.5 ° in relation to the celestial equator, changes in the altitude of the position of the sun occur at noon over the course of a year, which manifest as differences in the seasons. While the sun lingers over the horizon for more than 12 hours in the summer and stands high at noon, in winter the opposite is the case. This affects not only the day-night lengths, but also the amount of solar energy striking the earth and thus the temperature conditions of the individual seasons.
Solstices and their meaning
At the moment of a solstice, the distance between the sun and the celestial equator as well as the other hemisphere is greatest. At the time of each summer solstice, therefore, most of the daily ecliptic is above the horizon, which we perceive on Earth as the longest day, and therefore the shortest night. Conversely, at the moment of a winter solstice, it is mostly below the horizon, which manifests as the longest night and the shortest day. The relationship between the ecliptic and the horizon can best be seen on the poles when the sun crosses the polar circles.
According to the Gregorian calendar in use today, the solstices mark the beginning of summer and winter and take place depending on the switching rules on 21 or 22 June and December.
The Romans and Greeks called the solstices the Solstice, which translates to "standstill of the sun". This Latin word is still used today in many languages. It is not only since antiquity that people orient themselves on the solstices to meet the right time for sowing and harvesting. Especially in the cultures in the north, where the climatic changes perceived by solstices can be seen more clearly than in the south, feasts and rites have been taking place since early times to celebrate these times and their effects on people's lives.