The Northern Hemisphere receives more daylight than any other day of the year on the summer solstice. This day marks the start of astronomical summer and the tipping point at which days start to become shorter and nights longer.

The word “solstice” comes from the Latin words “sol” (sun) and “stitium” (still or stopped). The ancients noticed that as summer progressed, the sun stopped moving northward in the sky, then begin tracking southward again as summer turned to autumn. (During the winter solstice, the sun does the opposite, and begins moving northward as winter slowly turns to spring.)

Neolithic humans may initially have started to observe the summer solstice as a marker to figure out when to plant and harvest crops. In Ancient Egypt, the summer solstice corresponded with the rise of the Nile River. Its observance may have helped to predict annual flooding.

Different cultures and religious traditions have different names for the summer solstice. In Northern Europe, it’s often referred to as Midsummer. Wiccans and other Neopagan groups call it Litha, while some Christian churches recognize the summer solstice as St. John’s Day to commemorate the birth of John the Baptist.

According to some ancient Greek calendars, the summer solstice marked the start of the New Year. The summer solstice also marked the one-month countdown to the opening of the Olympic games.

Kronia, a festival celebrating Cronus, the god of agriculture, was also held around this time. The Greeks’ strict social code was temporarily turned on its head during Kronia, with slaves participating in the merriment as equals or even being served by their masters.

In the days leading up to the summer solstice, the ancient Romans celebrated Vestalia, a religious festival in honor of Vesta, goddess of the hearth. During Vestalia, married women could enter the temple of Vesta and leave offerings to the goddess in exchange for blessings for their families.

In ancient China, the summer solstice was associated with “yin,” the feminine force. Festivities celebrated Earth, femininity, and the “yin” force.

Before Christianity, ancient Northern and Central European pagans (including Germanic, Celtic and Slavic groups) welcomed Midsummer with bonfires.  It was thought that bonfires would boost the sun’s energy for the rest of the growing season and guarantee a good harvest for the fall.

Bonfires also were associated with magic. It was believed that bonfires could help banish demons and evil spirits and lead maidens to their future husbands. Magic was thought to be strongest during the summer solstice.

Midsummer was a crucial time of year for the Vikings, who would meet to discuss legal matters and resolve disputes around the summer solstice.

Many Native American tribes took part in solstice rituals, some of which are still practiced today. The Sioux, for instance, performed a ceremonial sun dance around a tree while wearing symbolic colors.

Some scholars believe that Wyoming’s Bighorn Medicine Wheel, an arrangement of stones built several hundred years ago by Plains Indians that aligns with the summer solstice sunrise and sunset, was the site of that culture’s annual sun dance.

According to pagan folklore, evil spirits would appear on the summer solstice. To ward off evil spirits, people would wear protective garlands of herbs and flowers.

One of the most powerful of these plants was known as ‘chase devil.’ Today it’s called St. John’s Wort, because of its association with St. John’s Day.

Other summer solstice traditions hold that the ashes from a Midsummer bonfire can protect one from misfortune or that the ashes—when spread across one’s garden—will bring a bountiful harvest.

The orientation of some archaeological structures are thought to reflect ancient observations of the summer solstice.

From the view of the Sphinx, the sun sets squarely between the Great Pyramids of Khufu and Khafre on Egypt’s Giza plateau on the summer solstice.

Archeologists have long debated the purpose and uses of Stonehenge, a Neolithic megalith monument in the south of England. The site is aligned with the direction of the sunrise on the summer solstice.

While some have theorized that Stonehenge was the location of prehistoric summer solstice rituals, there’s little archaeological evidence that it was used this way.

Many cultures still celebrate the summer solstice. Midsummer festivities are especially popular in Northern Europe where bonfires are lit, girls wear flowers in their hair and homes are decorated with garlands and other greenery.

In some parts of Scandinavia, Maypoles are erected and people dance around them at Midsummer instead of May Day. Neopagans, Wiccans and New Agers around the world hold summer solstice celebrations. Each year, thousands gather at Stonehenge to commemorate the longest day of the year.

Why we celebrate the summer solstice. Scientific American.
Summer Solstice 2011: Why It’s the First Day of Summer. National Geographic.
Traditions and Holidays Around the June Solstice. TimeAndDate.com.