How and why humans celebrate the summer solstice

LOS ANGELES - The summer solstice is the longest day of the year, and the official start of summer. People have been celebrating the summer solstice since the Stone Age. But how much do you know about the summer solstice and its history? Here's what you might not know:

On the summer solstice, the northern half of the Earth is tilted the closest it will be to the sun all year. In the Southern Hemisphere, the reverse is true, making the same day the winter solstice for everyone south of the equator.

Although the northern hemisphere is angled towards the sun the most on the solstice, the earth itself is actually at its furthest distance from the sun.

The word "solstice" comes from Latin, meaning "sun stands still," since ancient people noticed that the position of the sun at noon did not change during the solstice and the days surrounding it.

In ancient Egypt, the summer solstice meant the upcoming appearance of the star Sirius in the sky, which marked the end of the calendar year. Ancient humans around the world often lit bonfires on the solstice to help give energy to the sun for the rest of the year.

To this day, tens of thousands of modern pagans gather at Stonehenge to celebrate the solstice, since they believe the mysterious monument was part of ancient solstice celebrations.

Whether or not you're officially celebrating, everyone can enjoy the solstice… just make sure to remember your sunscreen!