A solstice is an astronomical event that occurs twice each year as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere.
The June (summer) solstice marks the first day of the summer season in the northern hemisphere. Summer solstice always occurs between June 20–22. This year’s summer solstice will be Friday, June 21st.
NOTE: The last time there was a June 22 solstice was in 1971 and the next one won’t happen until 2203!
Why varying dates?
Mainly because of the the calendar system – most western countries use the Gregorian calendar, which has 365 days in a year, or 366 days in a leap year. As for the tropical year, it is approximately 365.242199 days, but varies from year to year because of the influence of other planets. A tropical year is the length of time that the sun takes to return to the same position in the cycle of seasons, as seen from Earth. The exact orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth’s axis (precession), also contributes to the changing solstice dates.
The June solstice explained
The June solstice occurs when the sun is at its furthest point from the equator – it reaches its northernmost point and the Earth’s North Pole tilts directly towards the sun, at about 23.5 degrees. It is also known as the northern solstice because it occurs when the sun is directly over the Tropic of Cancer in the northern hemisphere. If the Earth’s rotation was at right angles to the plane of its orbit around the sun, there would be no solstice days and no seasons.
The June solstice day has the longest hours of daylight for those living north of the equator. Those living or traveling to the north of the Arctic Circle see the “midnight sun”, where the sun remains visible throughout the night, while those living or traveling south of the Antarctic Circle will not see sun during this time of the year. For those seeking the least fluctuations in temperature, they need to live near the equator, where the sun does not shift up and down in the sky as much compared with other geographical locations away from the equator during this time of the year.
The word solstice is from the Latin word “solstitium”, meaning “sun-stopping”, because the point at which the sun appears to rise and set stops and reverses direction after this day. On this day, the sun does not rise precisely in the east, but rises to the north of east and sets to the north of west allowing it to be in the sky for a longer period of time. In the southern hemisphere, the June solstice is known as the shortest day of the year. It is when the sun has reached its furthest point from the equator and marks the first day of winter.
Solstice’s influence on cultures
It is amazing the amount of knowledge that the generations have accumulated on the celestial bodies. When you consider the rudimentary tools and recording devices, it has been a phenomenal feat when you see just how much our ancestors actually figured out about the world around them.
But, it is also important to note that this information wasn’t something that was “interesting”. Their lives were so dependent on crops and the seasons; learning just how it all worked was crucial to survival. Celebrating solstice became a central theme in cultures throughout the world. As someone who truly cares about the environment, I wish we had more focus on these seemingly unimportant passages of time and passing of seasons. Understanding and celebrating those events would help us to better connect and protect this planet we call home.