Summer Solstice a Time of Pilgrimage for Many

The summer solstice arrived this week, marking the longest day of the year, and while for many this may mean no more than an entertaining doodle on Google, for others it marks a day of pilgrimage.

Summer officially begins when the summer solstice occurs, which this year took place on June 21, 1:04 a.m. EDT, and is the result of Earths' north-south axis being tilted 23.4 degrees relative to the ecliptic, or the plane of the solar system.

As a result of this tilt, different amounts of sunlight reach different regions of the planet during the Earth's orbit. However, come the solstice, the Earth is tilted toward the Sun more than it ever will be, meaning the northern hemisphere will be exposed to more sunlight than at any other day in the year.

This exact positioning of the sky, though its timing varies year to year, means that, over the entire course of human history, the Sun and its position in the sky has reached the same peak before winter comes and it starts to drop lower and lower, heating the hemisphere less and less.

As a result, civilizations throughout the world have built homages to this zenith, and while modern technology means humanity today is less dependent on sunlight throughout than it was 1,000 or even 100 years ago, many still celebrate the astronomical holiday at ancient sites that are either known or believed to be related to the event.

Stonhenge, for example, drew a crowd of 20,000 people this year, according to the Associated Press. And while the day turned out to be overcast, the masses included druids looking to worship as well as those looking for a party.

Meanwhile, the head of a serpent face in Ohio is one ancient earthwork known to face the summer solstice sunset where those looking to celebrate can visit.

And then there are the six pyramid-shaped structures on the island of Tenerife in the Canary Islands where, at summer solstice, a double sunset appears to occur from the view of the largest platform as the sun sets behind a mountaintop only to emerge and set again behind a nearby peak.