Understanding the Science behind the Summer Solstice
What happens to the sun?
During the summer solstice, the sun appears high in the sky at noon in the Northern Hemisphere. This is in contrast to the winter solstice, when the noon sun appears low in the sky. The sun’s position in the sky during the solstice affects the number of hours of daylight experienced on this day.
Why does the date vary?
The summer solstice in the Northern Hemisphere falls on either June 20 or June 21 each year. In the Southern Hemisphere, it occurs on December 21 or December 22. The variation in the date is due to the fact that the Gregorian calendar, which is used globally, has 365 days, with an additional leap day added in February every four years. However, Earth’s orbit around the sun takes approximately 365.25 days, leading to a slight discrepancy in the solstice dates.
Earth’s distance from the sun
Contrary to popular belief, the Earth is farthest from the sun during the summer in the Northern Hemisphere. On average, Earth is about 93 million miles (150 million kilometers) away from the sun. However, aphelion, the point at which Earth is farthest from the sun, occurs on July 6, approximately two weeks after the June solstice. During aphelion, Earth is about 94,506,364 miles (152,093,251 km) away from the sun.
How long is summer?
There are two definitions for the duration of summer: astronomical and meteorological. Astronomically, summer in the Northern Hemisphere starts on the summer solstice and ends on the fall equinox. Therefore, summer lasts from either June 20 or June 21 until September 21, 22, 23, or 24. However, the length of the seasons can vary slightly due to Earth’s elliptical orbit and varying speed. On average, summer lasts about 93.6 days in the Northern Hemisphere.
The meteorological definition of summer used by the U.K.’s Met Office is from June 1 to August 31. This definition provides a standard three-month timeline for each season.
The Significance of the Solstice
What does “solstice” mean?
The word “solstice” is derived from Latin and means “sun stands still.” This refers to the fact that during the solstice, the sun appears to rise and set at its farthest northeast and northwest points of the year. These points gradually shift back to rise and set due east at the following equinox.
Why isn’t the summer solstice the warmest day?
Despite the abundance of sunlight during the summer solstice, it is not necessarily the warmest day of the year. This is due to a phenomenon known as “seasonal lag.” It takes time for Earth’s land and water to heat up in response to increased sunlight. Additionally, after the solstice, the days gradually become shorter, and the Northern Hemisphere begins to tilt away from the sun, causing a decrease in warm weather.
Summer Solstice Celebrations
Stonehenge and Other Cultural Traditions
Many cultures have long recognized and celebrated the summer solstice. One of the most famous examples is the ancient site of Stonehenge in England, where the sun’s rays align with the Heel Stone on the solstice. This event is livestreamed on the official English Heritage YouTube channel. Other cultural traditions include witnessing the sun’s alignment with ancient pyramids in Egypt and various festivities and ceremonies held worldwide to honor the longest day of the year.
Conclusion
Understanding the science behind the summer solstice allows us to appreciate the celestial events that shape our seasons and encourage us to reflect on the wonders of our natural world. The solstice serves as a reminder of the beauty and complexity of Earth’s relationship with the sun, as well as the cultural significance attributed to this astronomical event across different societies. As we celebrate the summer solstice, let us take a moment to embrace the changing seasons and the unique moments of light and warmth they bring.
<< photo by Konevi >>
The image is for illustrative purposes only and does not depict the actual situation.
