This Thursday is the Summer Solstice – the longest day of the year in the Northern Hemisphere. While this happens every year, this particular solstice is rare. There hasn’t been one this early in 228 years.
George Washington was the president of the U.S. the last time a solstice was this early, USA Today noted. On that date, (June 20, 1796), there were only 16 states in the Union and a few weeks later, the U.S. took possession of Detroit, Mich., from Great Britain.
“The early solstice is due to the complex dance between Earth’s yearly orbit around the sun and its daily rotation, along with how we mark the solstice on our calendars,” said USA Today. “Quirks in the Gregorian calendar mean the solstice will make another jump earlier every leap year until the year 2100.”
Since the solstice is determined by when the sun reaches its northernmost point from the celestial equator, which doesn’t exactly line up to our calendar days. So, it slides between June 20, 21, and 22. This position of the sun makes the Northern Hemisphere warmer, thus bringing on the summer season.
According to the National Oceanic and Atmospheric Association, the summer solstice occurs at the moment the Earth’s tilt toward the sun is at a maximum level, resulting in the longest day of the year. Per the Old Farmer’s Almanac, the solstice officially occurs at 4:51 p.m. EDT and it marks the start of astronomical summer. Meteorological summer, on the other hand, began on June 1.
Thursday might be the longest day of the year, but the coming days will also be lengthy, said the NOAA.
“On the day of the summer solstice, the sun appears at its highest elevation with a noontime position that changes very little for several days before and after the summer solstice,” it said. “In fact, the word solstice comes from Latin solstitium or sol (the sun) + -stit-, -stes (standing). The summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° latitude North, and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China.”
In the Southern Hemisphere, the June solstice marks the beginning of winter. Another day, June 24, marks “Midsummer Day” or the midpoint of the growing season in the Northern Hemisphere.
“After the solstice, the Sun appears to reverse course and head back in the opposite direction,” explained the Old Farmer’s Almanac. It added that: “Of course, the Sun itself is not moving (unless you consider its orbit around the Milky Way galaxy); instead, this change in position in the sky that we on Earth notice is caused by the tilt of Earth’s axis as it orbits the Sun, as well as Earth’s elliptical, rather than circular, orbit.”
Summer days may be long, but the solstice doesn’t bring the earliest sunrise, which occurs about a week before the start of astronomical summer. Around the solstice time, the sun will set slower, since the angle it is at will make it take longer to dip below the horizon.
Here in the U.S., people across the country can enjoy a late sunset, expected at around 8:30 p.m. Thursday.