Solstice

The sun moves in the sky.

It changes every day. Sometimes the days are very long. Other times the days are very short. This helps make our seasons.

A solstice is a special day. On this day, the sun seems to stop. Then it starts to move the other way.

This happens twice every year.

One happens in June. This is the summer solstice. It is the longest day of the year. The sun stays up for a long time.

The other happens in December. This is the winter solstice. It is the shortest day of the year. The sun goes down very soon.

In the north, it is summer in June. In the south, it is winter then. The two sides of the world are different.

The sun helps us know the time of year.

A solstice is a special time each year. It happens twice every year. These dates are around June 20 to 22 and December 20 to 22.

The word comes from Latin. It means "sun-standing." This is because the Sun seems to stop moving up or down. Then, it changes direction and moves the other way.

This happens because the Earth is tilted. The Earth's axis, or the line it spins on, is not straight up and down. It leans at an angle. As Earth moves around the Sun, this tilt changes how much light we get.

In the June solstice, the North Pole leans toward the Sun. This makes the days very long. We call this the summer solstice. In the December solstice, the North Pole leans away. This makes the days very short. We call this the winter solstice.

At the North Pole, the Sun can stay up for 24 hours in June. This is called the midnight sun. In the winter, the Sun may not rise at all. This is called the polar night.

A solstice is a special time when the Sun reaches its highest or lowest point in the sky. This happens twice every year, around June 20–22 and December 20–22.

For many people, these dates help define the seasons. If you live far from the equator, the June solstice brings the longest day of the year. This is often called the summer solstice. In the other hemisphere, that same date is the winter solstice with the shortest day. The term can also describe the specific day when this event occurs.

This happens because of the way the Earth moves through space. The Earth orbits the Sun in an elliptical path. At the same time, the Earth's axis is tilted at an angle of about 23.44 degrees. This tilt is called the obliquity of the ecliptic. Because the axis keeps its direction while Earth orbits, different parts of the world lean toward the Sun at different times.

At the June solstice, the subsolar point is at the Tropic of Cancer, which is 23.44 degrees north. At the December solstice, it reaches the Tropic of Capricorn at 23.44 degrees south. This tilt causes the Sun's path to appear to move north and south throughout the year.

The word solstice comes from the Latin words "sol" and "stitium." Together, they mean "sun-standing."

This name describes what an observer sees in the sky. As the Earth orbits, the Sun's daily path seems to move higher or lower. At the moment of the solstice, this vertical motion appears to stop for an instant. After it reaches this limit, the Sun's path reverses direction. This is why the word implies a "stoppage" of the Sun's movement.

Ancient people studied these patterns very closely. The Ancient Greeks used the term "heliostāsio," which also meant the stand of the Sun. They understood that the Earth was a sphere. They imagined a celestial sphere where stars moved in circles. They noticed the Sun and planets moved along a different path called the ecliptic. This path is at an angle to the Earth's axis. This explains why the Sun appears to pass through the different signs of the Zodiac.

You can see the effects of solstices in extreme places like the poles. At the North Pole, the Sun reaches its highest point in the sky during the June solstice. In June, people in the Arctic Circle may see the "midnight sun." This means the Sun stays above the horizon for 24 hours. During the December solstice, the opposite happens at the South Pole. This is called the "polar night," where the Sun does not rise at all.

These cycles connect the movement of our planet to the light we feel every day.

A solstice is a specific moment in Earth's orbit. It occurs when the Sun reaches its most northerly or southerly position relative to the celestial equator. This event happens twice every year. These dates usually fall around June 20–22 and December 20–22. For most people living away from the equator, these events define the seasons. The June solstice often brings the longest daylight hours, while the December solstice brings the shortest.

The mechanism behind the solstice involves Earth's specific movement through space. Earth orbits the Sun in an elliptical path. However, Earth's axis of rotation is not straight up and down. It is tilted at an angle of approximately 23.44 degrees. This tilt is known as the obliquity of the ecliptic. As Earth orbits the Sun, this axis maintains its orientation in space. This means the tilt always points in the same direction relative to the stars. Because of this tilt, different parts of Earth lean toward the Sun at different times of the year.

This tilt creates distinct stages of solar position. At the June solstice, the subsolar point reaches its furthest north. The subsolar point is the exact location on Earth where the Sun is directly overhead. This point sits at latitude 23.44° north, a place called the Tropic of Cancer. At the December solstice, the subsolar point reaches its furthest south. This occurs at latitude 23.44° south, known as the Tropic of Capricorn. The subsolar point travels between these two extremes, crossing every latitude in between twice every year.

The name "solstice" has deep historical roots. It comes from the Latin words "sol," meaning Sun, and "stitium," meaning stoppage. This describes the apparent motion of the Sun in the sky. From our perspective on Earth, the Sun seems to move north or south throughout the year. At the moment of the solstice, this vertical motion appears to stop for an instant. Then, the Sun's path reverses direction. This is why the term implies a "sun-standing."

Ancient civilizations studied these solar patterns to navigate and understand time. The Ancient Greeks used the term "heliostāsio," which also meant the stand of the Sun. They understood that the Earth was a sphere. They imagined a celestial sphere where stars moved in parallel circles. They observed that the Sun and planets moved along a different path called the ecliptic. This ecliptic is tilted at an angle to the Earth's axis. This explains why the Sun appears to move through the constellations of the Zodiac.

The effects of solstices are most extreme at the Earth's poles. At the North Pole, the Sun reaches its highest annual position during the June solstice. Inside the Arctic Circle, people experience the "midnight sun." This is a period where the Sun stays above the horizon for 24 hours. Conversely, the December solstice brings the "polar night" to the Antarctic Circle. During this time, the Sun does not rise above the horizon at all. This lack of sunlight causes polar sea ice to re-grow every year.

Solstices are part of a larger cycle of solar events. There are two solstices and two equinoxes in a tropical year. An equinox occurs when the Sun's path crosses the equator. During an equinox, day and night are of equal length at most latitudes. While solstices mark the extremes of daylight, they do not immediately cause the hottest or coldest weather. The warmest and coldest periods in temperate regions are often delayed by about one month. This delay is caused by Earth's thermal inertia, which is the way the planet holds onto heat.