On June 21, 2020, somewhere around 5:43 in the morning in Britain, the sun rose over a circle of huge gray stones on a windy English plain. This was Stonehenge, and people had been gathering here at sunrise on the longest day of the year for thousands of years. The day is called the summer solstice - the moment when the North Pole tips closest to the sun, giving the Northern Hemisphere its longest hours of daylight. In some parts of Norway, the sun doesn't set at all.
Nobody is completely sure who built Stonehenge or why, but it went up in stages starting about 5,000 years ago. The biggest stones weigh up to 25 tons and were dragged from a quarry 18 miles away - without wheels or trucks. What scientists do know is that the whole circle is lined up perfectly with the sunrise on the solstice. Stand inside the ring on June 21, and the first ray of sunshine pours straight down a wide avenue and lights up an altar stone in the middle. It is hard to imagine that happened by accident.
All over the world, people have built their own solstice celebrations. In Sweden, families dance around tall flower poles called midsommarstång. In Peru, Inca descendants greet the sun at the temple of Inti Raymi. In Iceland, kids stay up until midnight to watch a sun that won't quite go down. The summer solstice marks the beginning of astronomical summer - and a quiet reminder that humans have been keeping an eye on the sky for a very, very long time.
