Summer solstice, full Moon happening together for first time since 1967 on Monday
TENNESSEE VALLEY– The 2016 North American summer solstice happens on June 20, 2016 at 5:34 p.m. CDT. That’s the very moment when, essentially, the sun stands still at its northernmost point as seen from Earth. Its zenith doesn’t yearn north or south, but waits patiently at the Tropic of Cancer before switching directions and heading south again.
This is where the word solstice comes from; the Latin solstitium, from sol (sun) and stitium (to stop).
What is a solstice?
Ancient cultures knew that the sun’s path across the sky, the length of daylight, and the location of the sunrise and sunset all shifted in a regular way throughout the year.
They built monuments, such as Stonehenge, to follow the sun’s yearly progress.
Today, we know that the solstice is an astronomical event, caused by Earth’s tilt on its axis and its motion in orbit around the sun.
Because Earth doesn’t orbit upright. Instead, our world is tilted on its axis by 23-and-a-half degrees, Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly.
At the June solstice, Earth is positioned in its orbit so that our world’s North Pole is leaning most toward the sun. As seen from Earth, the sun is directly overhead at noon 23 1/2 degrees north of the equator, at an imaginary line encircling the globe known as the Tropic of Cancer – named after the constellation Cancer the Crab. This is as far north as the sun ever gets.
All locations north of the equator have days longer than 12 hours at the June solstice. Meanwhile, all locations south of the equator have days shorter than 12 hours.
What makes this rare?
The summer solstice alone is iconic enough. It’s a day with a time-honored history rife with pagan celebrations and all things Stonehenge. But this year we get the big beautiful bonus of a full moon, which hits its peak on the same day.
The June full Moon was known as the Strawberry Moon to early Native American tribes, who measured time by things like the moon, rather than a grid on a piece of paper or an electronic device. The full moon that happened now marked the season of strawberries – as it still does.
The summer solstice marks the day with the most hours of daylight in the Northern Hemisphere. In the Tennessee Valley, expect 14 hours and 29 minutes of daylight Monday. For perspective, we get about 12 hours and 12 minutes of daylight on both the Autumnal and Vernal equinoxes.
The winter solstice marks the day with the least amount of daylight; north Alabama only gets 9 hours and 50 minutes of daylight in late December.