Earth & Sky

Everything you need to know about the solstice on June 20, 2008

Early dawn. Late sunset. Long day. Short night. For us in the northern hemisphere, the June solstice marks the longest day of the year.

It’s your signal to celebrate the first day of summer in this hemisphere. South of the equator, winter begins.

When is the solstice where I live?

The solstice happens at the same instant for all of us, everywhere on Earth. But our clocks say different times.

This solstice takes place on Friday, June 20, 2008 at 23:59 Universal Time. If you’re not accustomed to the 24-hour designation, the June solstice falls at 11:59 p.m. Universal Time and 6:59 p.m. Central Daylight Time.

To find the time in your location, you have to “translate” to your time zone.

Here’s an example. In the central United States, for those using Central Daylight Time, you’d subtract 5 hours from Universal Time. That how we get 6:59 p.m. Central Daylight Time as the time of this 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 23:59 Universal Time, Friday, June 20.

What is a solstice?

The earliest humans 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, 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-and-a-half degrees toward the sun. As seen from Earth, the sun is directly overhead at noon 23-and-a-half degrees north of the equator, at an imaginary line encircling the globe known as the Tropic of Cancer. This is as far north as the sun ever gets.

All locations north of the equator have day lengths greater than 12 hours at the June solstice. Meanwhile, all locations south of the equator have day lengths less than 12 hours

Where should I look to see signs of the solstice in nature?

Everywhere.

For all of Earth’s creatures, nothing is so fundamental as the length of daylight. After all, the sun is the ultimate source of all light and warmth on Earth.

If you live in the northern hemisphere, you can 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 is the solstice a big deal?

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 of the year, why is it that we usually receive the hottest weather not on that day, but 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 awhile to warm up after a long winter. Right now, 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 moving in orbit around the sun, bringing us closer to another winter.

And so the cycle continues.

Visit our summer solstice sun gallery.

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