Earth is back to rationing daylight. After summer’s surplus, we see and feel it slipping away in earlier sunsets and later sunrises. Less apparent but just as significant is the length of twilight. It gets darker faster now to the tune of a half-hour at both dusk and dawn.
Like you, I’ve seen this seasonal tip toward fall, but it really hit me on a recent morning. I got up after moonset to watch the Perseid meteor shower from a dark sky. When I arrived back home in the early light of dawn, I was struck by the absence of birdsong. We get used to hearing the early birds during spring and much of the summer. This morning, they were silent. Sigh.
These seasonal changes stem from a titled planet on a great yearly journey. Earth has traveled 584 million miles in its orbit around the sun every time you celebrate a birthday. Throughout, its axis, tipped 23.5 degrees, remains steadfastly pointed at the North Star. On the June-July side of its orbit, the northern hemisphere faces toward the sun and the southern hemisphere away. When a subject genuflects before his king, the king appears tall and powerful. When Earth bows before its sun, it appears high in the sky. A high path brings more intense heat and long hours of daylight.
In winter, the northern half of the planet is tipped away from the sun as if recoiling from the king’s anger. The sun appears low in the sky, rising late and setting early. Of course, seasonal changes due to the Earth’s tilt are slow and leave many signs along the way. Recognizing these signs in the sky is one of the joys of being a star-watcher. Constellations change with the season, planets shift about, day-length rubber-bands, the sun climbs high, the moon drops low and on and on.
Despite missing the birds, I like the shorter days. It makes it a whole lot easier to star-watch without having to wait until after 11 for a dark sky. Later sunrises also mean more time to catch up on sleep after pre-dawn forays.