The Summer Solstice
Tuesday, 21 June, marks 2023’s summer solstice. The word solstice comes from the Latin solstitium, which combines sol (sun) and stit (stopped or stationary). Technically defined, the summer solstice is the point when one of Earth’s poles is tilted maximally toward the sun. Broadly defined, it is the day on which the sun reaches the highest position in the sky above the hemisphere in question and on which the longest period of daylight occurs. In the other hemisphere, the exact opposite occurs: the winter solstice.
The summer solstice marks the end of astronomical spring. For the next three months, we are officially in summer. Somewhat paradoxically, during summer the days actually start to become shorter. While we are currently in the sweet spot for long days, that length only decreases for the next half year.
Check out the following short video for graphics on the tilting of the earth and how it causes seasons:
Also somewhat paradoxically, we tend to view the locations closer to the equator (for those of us in North America, to the south) as sunnier, but, especially right now, the farther north one lives the longer the sun shines. For example, New York City is currently experiencing an hour and a half more sunlight per day than Miami. Above the Arctic Circle, at the moment, it is perpetual daylight.
Because the exact instant the tilt is at maximum is the precise moment of the solstice and because of the shift in our calendars (a year is not exactly 365 days), the solstice is not always on the same day each year. The solstice does, however, occur within a range of dates: June 20 through June 22.
The date is also known by other names, including Midsummer or the estival solstice. Cultures around the world celebrate this astronomical event with festivals, rituals, and holidays. Many ancient structures were constructed by ancient peoples to align with the heavens, notably often with the sun on the summer solstice.
One of the most famous examples is Stonehenge. According to earthsky.com:
“Stonehenge, in England, was built in three phases between about 3,000 B.C. and 1,600 B.C., and its purpose remains under study. However, it’s known that if you stand in just the right place inside the Stonehenge monument on the day of the northern summer solstice, facing northeast through the entrance towards a rough-hewn stone outside the circle – known as the Heel Stone – you will see the sunrise above the Heel Stone.”
For those unable to travel to Stonehenge for the big day, the British conveniently live-stream the event! Check out videos from Stonehenge on the solstice, one at sunrise, the other at sunset.
Happy summer! Unless you’re in the southern hemisphere. In that case, happy winter!
Further Reading and Exploration
2023 June solstice: All you need to know – EarthSky
Dates and times of solstices since 1600
Stonehenge – official website
What is the summer solstice? Here’s what you need to know. – National Geographic article