Here in the northern hemisphere the most northerly point of the Sun’s path across the sky is rapidly approaching. June 21 marks the longest day and the shortest night of the year. This same day brings the shortest day of winter for you folks in the southern hemisphere, with the longest night to follow. I’ve noticed the change of the day length more directly lately, since the sunset point is now almost directly aligned with one of the windows in my office and if I’m working after dinner (which I almost always am), it’s shining right in my eyes.
So, solstice is the latin word for “sun still.” It doesn’t mean the Sun literally stops in the sky. It couldn’t, since the Sun’s apparent motion across the sky is caused by the Earth’s turning on its axis. It only LOOKS like the Sun is crossing from East to West each day.
If you watch the sunrise and sunset points each day for a year, you’ll notice that the Sun rises and sets farther and farther north from December 21 to June 21, and then rises and sets farther and farther north from June 21 to December 21 (if you’re in the northern hemisphere). On December 21 and June 21, the Sun seems to pause in its southern and northern migrations. Those are the solstice times.
Why the north-south migration? Again, it’s the motion of the Earth that makes it look like the Sun is wandering north-south. There’s a cool little movie here that shows how the tilt of our planet’s equatorial plane with respect to the Sun is responsible for the change of seasons. It also affects which part of the Earth is tilted toward the Sun throughout the year.
Now, it’s no coincidence that some of the best parties of the year are held around the solstices. In ancient times, the winter solstice was the darkest, coldest time of year, and people held parties (or performed ceremonies) to mark the time and hope for a new year to begin (with its promise of warmth and life). At the summer solstice, people partied because the weather was good, crops were growing, food was plentiful. We still celebrate at both solstices today (and some religions have ceremonies and rituals at these times, too). I like to think of these times as celebrations of motion in the universe—motions of our planet around the Sun and on its axis. And every planet does this, so every planet has solstices, each in its own way.
Modern folks aren’t so tuned to the change of seasons as the ancients were. But, we can still go outside each day and make notes of sunrise and sunset positions throughout the year. And, there’s still time to party at summer and winter solstice, just like our ancestors did. So, if you’re in the northern hemisphere, take time out on the 21st of June to celebrate the longest day of the year. If you’re south of the equator, here’s hoping you’re warm, safe, and looking forward to the spring and summertime weather you’ll be enjoying while we have autumn and winter later this year.
