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Since I can remember, I’ve liked to observe the
sky, the stars, and the movement of the sun and the moon. There is
no claim here that I’m an ace astronomer; I am merely the casual
observer to whom some things are intuitively obvious. Here in the
Netherlands we are at 52 degrees north latitude, and the sky and
behavior of the sun is clearly different to the casual observer than
what it is in Philadelphia. When we moved here in November it rained
frequently and the sky was almost always filled with thick dark
clouds. As spring becomes more evident, the clouds are less
prevalent and the casual observer gets to see what’s happening. The
first thing that was apparent was that the north star is much higher
in the sky which makes sense because, being the north star, if one
were at the North Pole, it would be directly overhead.
You may know that the difference in the length of
day and night from summer to winter is more drastic the closer to
the pole one gets. At the equator there are 12 hour days and nights
all year. In Philadelphia, at 40 degrees north, it’s about 16 hour
days and nine hour nights in summer with the reverse in winter. Here
it’s about 18 hour days and six hour nights in summer with the
reverse in winter. At this early date in mid-April, the sky is still
light at 9 p.m. In Philadelphia, that won’t happen until June and
for those of you farther south, it may not happen at all that it’s
still light at that time.
There’s another oddity of the sun as one goes
closer to the pole; the sun never gets as high in the sky. Assuming
noon, at the equator the sun is always at least 66 and a half
degrees above the horizon. That’s pretty high in the sky. At the
vernal and autumnal equinoxes it’s directly overhead at 90 degrees.
It rises almost vertically, goes across almost the center of the sky
and sets almost vertically causing it to get "dark fast" after
sunset as the sun moves straight down below the horizon. In
Philadelphia, in summer the sun rises to a maximum of 73 and a half
degrees and in winter to a maximum of 28 and half. In the
Netherlands, 12 degrees closer to the pole, those numbers are 61 and
a half, and 16 and a half. Think about that. In winter, the sun gets
to only 16 and a half degrees above the horizon, barely high enough
to clear treetops, and certainly not enough to clear tall buildings
in a single bound. The shadows, assuming winter sun in the
Netherlands which is a bad assumption, are always long. But here it
gets "dark slow." That’s because the sun neither rises nor sets
vertically but rather on an angle. The closer to the pole one goes,
the more horizontal the angle until, within the Arctic (or
Antarctic) Circle, the angle is fully horizontal and the sun neither
rises nor sets for months at a time, hence, the land of the midnight
sun. Here in the Netherlands, the sun will set but it will be
twilight for what seems sometimes like forever because the sun is
traveling a path close to the horizon but just below it. When we
were here visiting last summer, it was still twilight approaching 11
p.m.
Those are the astronomical facts. But what does
it mean to the average person on the street? It means that when
taking pictures in winter, it can be difficult to get good lighting
because of the long shadows, even at noon. But that’s not a reason
to stay away because where else can you get photos of octogenarians
on bicycles in the rain with their groceries or small rivers running
down the middle of almost every street? |
