Winter Solstice 2023

The angle of the Earth’s tilt with respect to the sun hits its maximum southern point today at 10:28 pm, marking the Winter Solstice in the Northern Hemisphere. Here’s a couple of images from the GOES satellites I thought were pretty neat. To start, here’s an image from just before sunrise on the east coast today – the tilt is pretty dramatic:

This next shot takes some explanation. It was acquired at midnight, with the sun directly opposite from the satellite. So why is there a crescent earth visible, and why is it at the south pole? It’s because of the 23.5 degree tilt – you may have heard Norway called The Land of the Midnight Sun (Norway was the original, Alaska is called this also). At any place north of latitude 66.5 or south of latitude -66.5, for part of the year the sun never sets. This image shows that pretty dramatically – the south pole is lit up all day right now, even at midnight. 

An image taken in six months, on June 21st, would show the opposite: the north pole will be in daylight. While the sun is only above the horizon north/south of 66.5, the atmosphere refracts the sun’s rays and it is twilight or dusk at midnight further south – this the deep blue part of the arc in this image. Of course here in the northern hemisphere, at the poles it’s dark all day – and of course no sun at all visible, not even any twilight in the far north, as you can also see.

Our ancestors didn’t understand things like axial tilt or orbital mechanics, but they were intimately connected with their environment and understood the cycle of the seasons, building monuments like Stonehenge and other alignment circles to track them. Most human religions mark this time of year to reflect on the meaning of life and death; the coming of deep winter often bringing death, but the days are getting longer, signaling rebirth and renewal. Understanding the why shouldn’t detract from the wonder of nature, or the deeper philosophical meaning of the passage of time. Take a few minutes today to reflect on it all.