If you’re in the northern hemisphere, the June 21 solstice is your signal to celebrate summer. For us, this solstice marks the longest day of the year.
If you’re in the northern hemisphere, the June solstice is your signal to celebrate summer. For us, this solstice marks the longest day of the year. Early dawns. Long days. Late sunsets. Short nights. The sun at its height each day, as it crosses the sky. Meanwhile, south of the equator, winter begins.
When is the solstice where I live?
The 2011 June or summer solstice takes place on Tuesday, June 21, 2011 at 17:16 UTC (12:16 p.m. CDT).
It happens at the same instant for all of us, everywhere on Earth. To find the time of the solstice in your location, you have to translate to your time zone.
Here’s an example of how to do that. In the central United States, for those of us using Central Daylight Time, we subtract five hours from UTC. That’s how we get 12:16 p.m. Central Daylight Time as the time of the 2011 June solstice.
Want to know the time in your location? Check out EarthSky’s article How do I translate Universal Time into my time? And just remember: you’re translating from 17:16 Universal Time, Tuesday, June 21.
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.
Waiting for dawn to arrive at Stonehenge, summer solstice 2005. Image Credit: Andrew Dunn. Wikimedia Commons.
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, but is instead 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 the North Pole is leaning 23 1/2 degrees 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.
Where should I look to see signs of the solstice in nature?
For all of Earth’s creatures, nothing is so fundamental as the length of the day. After all, the sun is the ultimate source of almost all light and warmth on Earth’s surface.
If you live in the northern hemisphere, you might notice the early dawns and late sunsets, and the high arc of the sun across the sky each day. You might see how high the sun appears in the sky at local noon. And be sure to look at your noontime shadow. Around the time of the solstice, it’s your shortest noontime shadow of the year.
If you’re a person who’s tuned in to the out-of-doors, you know the peaceful, comforting feeling that accompanies these signs and signals of the year’s longest day.
Why celebrate the solstice?
Cultures universally have had markers, holidays, and alignments – all related to the solstice.
It has been universal among humans to treasure this time of warmth and light.
For us in the modern world, the solstice is a time to recall the reverence and understanding that early people had for the sky. Some 5,000 years ago, people placed huge stones in a circle on a broad plain in what’s now England and aligned them with the June solstice sunrise.
We may never comprehend the full significance of Stonehenge. But we do know that knowledge of this sort wasn’t isolated to just one part of the world. Around the same time Stonehenge was being constructed in England, two great pyramids and then the Sphinx were built on Egyptian sands. If you stood at the Sphinx on June 21 and gazed toward the two pyramids, you’d see the sun set exactly between them.
How does it end up hotter later in the summer, if June has the longest day?
People sometimes ask: “If June 21 is the longest day, why do we experience the hottest weather in late July and August?”
This effect is called “the lag of the seasons.” It’s the same reason it’s hotter in mid-afternoon than at noontime. Earth just takes a while to warm up after a long winter. Even in June, ice and snow still blanket the ground in some places. The sun has to melt the ice – and warm the oceans – and then we feel the most sweltering summer heat.
Ice and snow have been melting since spring began. Meltwater and rainwater have been percolating down through snow on tops of glaciers.
But the runoff from glaciers isn’t as great now as it’ll be in another month, even though sunlight is striking the northern hemisphere most directly around now.
So wait another month for the hottest weather. It’ll come when the days are already beginning to shorten again, as Earth continues to move in orbit around the sun, bringing us closer to another winter.
And so the cycle continues.
Read more at earthsky.org
Bottom line: The 2011 June or summer solstice takes place on Tuesday, June 21, 2011 at 17:16 UTC (12:16 p.m. CDT). This solstice – which marks the beginning of summer in the northern hemisphere – marks the sun’s most northerly point in Earth’s sky. It’s an event celebrated by people throughout the ages.