Earlier this week, the earth reached its aphelion, the point in its orbit that is furthest from the sun. This happens because the earth’s orbit is slightly elliptical; at the aphelion, we’re about two point one million kilometers further from the sun than usual. That might sound extreme, but remember: you didn’t notice. It happens every year, and you’ve never noticed.
I observed this year’s aphelion, a few moments of contemplation, at 10:27 p.m. on July 5. Two weeks prior, I stood on the beach of the North Sea as the sun rose on the June solstice—the date from which days go from getting longer to shorter in the northern hemisphere and shorter to longer in the southern hemisphere. That these events are close together but not overlapping might seem odd at first glance, but they have different causes: the solstice is determined by the earth’s axial tilt, while the aphelion is determined by our orbit.
If that’s still a bit vague, imagine a flat, almost-but-not-completely circular disc. The sun is at the center, and the earth completes one lap around the disc each year. The disc isn’t exactly aligned with the earth’s equator; instead, the earth is tilted, and that tilt is steady. If you imagine the north and south poles extending out of the earth, you’d find that they are not perpendicular to the disc but tilted at an angle of about 23.44°. The ends of the poles continue to point in the same directions no matter where the earth is positioned around the disc. For half the year, the north pole is moving away from the direction it points while the south moves toward its target; when the earth reaches a solstice, they switch.
Because the earth’s axial tilt never changes, the solstice is fairly consistent; it falls on or around June 21 and December 21 each year. The orbit, however, is drifting. Less than a thousand years ago, in 1246, the earth’s perihelion (its closest point to the sun) happened at the same time as the December solstice. In a few thousand years, the perihelion will be in mid-March.
Pausing for the aphelion was an interesting mind exercise, but it wasn’t tangible. The solstice was another story.
Here in northeast Scotland, the solstices are extreme. From May through mid-August, we don’t experience “night” in an official sense (when the sun is greater than eighteen degrees below the horizon); for all of June and half of July, the sky only reaches nautical twilight, meaning the sun is never more than twelve degrees below the horizon. On the June solstice, the sun crested the horizon at 4:12 a.m. and remained brilliantly in the sky until 10:08 p.m. that night, a day length of nearly eighteen hours. We trade these leisurely days for bitter darkness in the winter: on the December solstice, we will have less than seven hours of day; the sun will not reach more than ten degrees over the horizon and will set before 3:30 p.m.
On the morning of June 21, my friend and I got to the beach at four. Before us stretched the North Sea, dotted with wind turbines and a herd of anchored ships waiting for their turn in the harbor. The sky had been gray well into the prior evening, tempting us to abandon the plan altogether, but it was now bright and clear save for a fluff of clouds on the horizon. It was hard to tell, on the mile of city beach, whether we were alone in embracing this view, but it felt like solitude.
The first rays emerging behind the clouds were the most captivating. Once the sun rose to support them, we could no longer look directly; we were left with two and a half hours to occupy before the early bird coffee shops opened. Alone on the bright, warming beach, we danced and played games and basked in the sun. By six, it was already higher in the sky than it ever reaches in our winters.
Watching the sunrise was a practice of incandescent joy. My sense of place and community, of being well located in my life and in the world, were strengthened in those early morning hours. My fascination with astronomy makes our actual position in the solar system significant to me, but on that morning I was more enamored with the glistening granite city, the lull of the waves, the 5 a.m. runners bemusedly taking in the two euphoric figures scrambling over a groyne. This place is valuable; it is worthy of my investment of time, of money, of energy, of passion; it is home.