A Picturesque Equinox Sunset

What is that at the end of the road? The sun. On two days each year, the sun sets down in the middle of the road that runs east - west. Today is an equinox. Not only is today a day of equal night and day time, but also a day when the sun rises to the east and sets to the west. There is a road in northwest Illinois that runs east to west. The Sun can be seen down the road at sunset in the image. The first day of a season in many cultures is the March equinox, which is the first day of spring in the north and autumn in the south. Does your street go east or west? You can find out at sunset.

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Explanation: What if you could see the entire sky -- all at once -- for an entire year? That, very nearly, is what is pictured here. Every 15 minutes during 2021, an all-sky camera took an image of the sky over the Netherlands. Central columns from these images were then aligned and combined to create the featured keogram, with January at the top, December at the bottom, and the middle of the night running vertically just left of center. What do we see? Most obviously, the daytime sky is mostly blue, while the nighttime sky is mostly black. The twelve light bands crossing the night sky are caused by the glow of the Moon. The thinnest part of the black hourglass shape occurs during the summer solstice when days are the longest, while the thickest part occurs at the winter solstice. Yesterday was an equinox -- when night and day were equal -- and the northern-spring equinox from one year ago can actually be located in the keogram -- about three-quarters of the way up.