What do you know about the longest day of the year?
As the days continue to grow longer and the sun even hotter, there’s one day in particular that we look to that officially tells us summer has arrived. And no, it’s not the last day of school, although good luck convincing your kids otherwise.
We’re talking about the summer solstice, aka the longest day of the year. It typically occurs around June 20-22nd when the sun is at 23.5 degrees north latitude, directly over the Tropic of Cancer.
But other than owning that longest-day crown, what else do you really know about the summer solstice?
Answer: more than you probably care to know after reading this.
How does the summer solstice work?
Unless you’re a flat earther, then you know that the Earth and other planets in our solar system orbit around the sun. And that the earth also orbits on a tilted axis, more than likely due to a collision billions of years ago when the planet was still forming.
Well, as the earth orbits the sun over its 365 days, the northern hemisphere receives more exposure from the sun between March and September. This leads to longer days, with late June being among the longest (hence the solstice). Conversely, during the rest of the year, the southern hemisphere gets more fun in the sun – better known as our seasons.
Let it shine. How many hours of sunlight does the solstice provide?
During the summer solstice, the northern hemisphere reaps the sunny rewards, right? Well, simple science shows that the further north you live, the more hours of sunlight you’ll receive. Northern Canada and Alaska typically reach upwards of 18-22 hours of daylight during this time. And those that live even nearer to the Arctic Circle never really have a sunset during the solstice. Everyday bleeds into the previous one, marking quite the spectacle to behold. There’s a reason northerners are responsible for the increase in out-of-stock increase blackout curtain during the summer months.
Summer solstice and Stonehenge, wait what?
The mystery of Stonehenge is one of the greatest man made wonders of our planet. No one seems to truly know why the structure was erected thousands of years ago, but there are some interesting theories, and one of those involves marking solstices and equinoxes.
Why, you ask? Because during the summer solstice, the sun is perfectly over the structure’s heel stone resulting in a perfect, dead center beam of light hitting the altar stone. This theory is so adored by people that on the summer and winter solstices, Stonehenge literally becomes a party scene. We may not know what Stonehenge was built for back then, but we know it’s a hot party spot now during solstice.
What’s the longest day in earth’s history
Due to tidal friction, the earth has been gradually slowing down over millennia. Because of its liquid oceans and moon and their effects on gravity, earth’s days have been steadily growing longer (tiny fractions of milliseconds) due to this friction. If you look back about 5 billion years ago, an earth day was approximately 6 hours. Over a long, long time, we’ve reached what we now know as our 24-hour days.
So with that logic in mind, every new year summer solstice has to be the longest day in earth’s history, right? Not so fast (literally). You see, tidal friction isn’t the only thing affecting the earth’s rotation. And while this friction is slowing down the days, other factors like glacial melting and global warming are actually speeding up the earth’s rotation by fractions of milliseconds. Eventually tidal friction will win out, but this tug of war is why each new year’s summer solstice doesn’t take the crown for longest day of the year.
Instead, we have to look back more than 100 years to 1912 to find that award winner. That year, not only had the longest summer solstice but it also had the longest winter solstice (night) we’ve ever recorded.
So this summer while you’re catching a few rays down at the pool, know that the sun is working extra hours, putting in overtime to help you get that perfect tan.