I sit here writing this as the sun has just begun to slant toward the west. It is quite late in the evening. It is the summer solstice, the longest day in the year in the Northern Hemisphere. The further north, the longer the day.

For those of us who grew up in the temperate latitudes, this day was not a day of crazy joy, enhanced by drinking songs as it apparently is in Sweden. On this day, near the North Pole, the sun never sets. But for those in Arizona, where I live now, it is a day to stay out of the sun.

The earth is a slow seesaw. At the summer solstice in this hemisphere, the North Pole tilts 23.4 degrees, allowing the sun’s rays to shine vertically over the Tropic of Cancer at noon on June 21. South of the equator, December 21 is when the South Pole tilts 23.4 degrees, its maximum tilt. The sun beams directly over the Tropic of Capricorn, giving those in southern climes their longest day in the sun.

I grew up in Australia. There, today the winter solstice marks the shortest day of the year.

Ancient peoples everywhere marked the solstice. It’s said that when the Vikings converted to Christianity, they adopted their Yule celebration to Christmas. Yule marked the time when people could look forward to longer days and spring. Three thousand years earlier, in Egypt, the rebirth of the god Horus at the winter solstice was marked with twelve days of festivities festooned with greenery. Rome adopted this festival as Saturnalia. In Australia, too, which has been peopled for 60,000 years, a rock formation has been found that appears to mark the position the sun sets at both solstices. The oval ring formation of the basalt rocks, named Wurdi Youang by the traditional owners, is estimated to be around 11,000 years old.

Even today, the seasons, and their way of signifying time, rule our lives.

So thank the tilt of the earth for all those drinking songs saluting the joy of summer, and those cozy log fires and hot toddies acknowledging that the darkness will lighten with every passing night.