Solstice

A solstice is a special moment in the year when the Sun reaches its farthest point north or south in the sky. This happens because the Earth is tilted and changes how sunlight reaches different places.

There are two solstices every year, usually around June 20–22 and December 20–22.

Many people use the solstices to mark the changing of the seasons. The summer solstice, in June, is when some places get the most daylight of the year. The winter solstice, in December, is when they get the least daylight. These events have been important for cultures and traditions for thousands of years.

The word solstice comes from Latin, meaning “sun standing still.” This is because the Sun's movement in the sky seems to pause for a little while during these days. Whether it is the longest day or the shortest day of the year, the solstice connects us all to the rhythm of Earth and the Sun.

Etymology

The word solstice comes from the Latin words sol (meaning "sun") and sistere (meaning "to stand still"). During the solstices, the Sun's path in the sky seems to pause before changing direction.

The term solstice entered the English language during the Middle English period. An older English word for this event was sunstead, which is rarely used today. Similar words exist in other Germanic languages, such as sólstaðr in Old Norse.

Definitions and frames of reference

For someone at the North Pole, the Sun looks highest in the sky once a year in June. This day is called the June solstice. For someone at the South Pole, the Sun is highest in December, called the December solstice. When it is summer at one pole, it is winter at the other.

The word "solstice" comes from Latin and means "sun-standing." This is because the Sun's upward movement in the sky seems to stop and then go the other way at these points. The Sun's path in the sky changes through the year because of Earth's tilt and its orbit around the Sun. The longest days happen around the summer solstice, and the shortest days around the winter solstice. Near the equator, these dates can change a little.

Relationship to seasons

Main article: Season

The seasons happen because Earth's axis is tilted. This tilt stays pointed in the same direction as Earth moves around the Sun.

For half the year, the Northern Hemisphere leans toward the Sun. For the other half, the Southern Hemisphere leans toward the Sun.

The two solstices are when this tilt has its biggest effect. At the June solstice, the Sun is directly overhead at latitude 23.44° north, called the Tropic of Cancer. At the December solstice, it is overhead at 23.44° south, the Tropic of Capricorn. During these times, areas inside the Arctic Circle can see the Sun all day. Areas inside the Antarctic Circle can have no sunlight at all.

Cultural aspects

The ancient Greeks were very interested in how the Sun and stars moved. They made up the idea of the celestial sphere to help explain these movements. They had special names for the times when the Sun is farthest in the sky, which we now call solstices.

Different cultures have different names for the solstices. In English, we often call them the summer solstice and winter solstice. Some cultures use the month's name, like June solstice and December solstice. Others use names like Northern solstice or Southern solstice.

In East Asia, the solstices are part of a system with 24 solar terms that divide the year. The summer solstice is called Xiàzhì, and the winter solstice is called Dōngzhì. These terms mark the middle of the seasons in their calendars.

Many cultures have festivals around the solstices. For example, Christmas is celebrated around the winter solstice in many places. In East Asia, the Dongzhi Festival happens on the winter solstice. Some people also celebrate Midsummer around the summer solstice. These festivals have been important for many years, helping people notice the changing seasons and feel connected to nature.

In the constellations

The place where the sun seems farthest north or south changes as Earth moves. This shift makes the solstices move through different groups of stars, called constellations.

Long ago, the northern solstice was in the constellation Leo. It later moved into Cancer, then Gemini, and today it is in Taurus. In the future, it will move into Aries. For the southern solstice, it used to be in Capricornus and is now moving toward Sagittarius, and will later enter Ophiuchus and Scorpius.