As we exit this season of dark, in the northern hemisphere, and welcome back the growing light of day, I must share with you all something I came across back around the winter solstice: The South Pole has no balance in its life.
I didn’t believe this when I read it, but I found a 1999 blog post from NASA (or whatever they were calling it back then [what they were calling blog posts, I mean, I know NASA’s name hasn’t changed]), and NASA confirmed it. The South Pole has one day every year, traditionally defined. The sun rises once a year and it sets once a year. When it’s light, it’s light for six months. When it’s dark, it’s dark for six months. I don’t know how long twilight lasts. It looks like it might actually last for months, if I’m reading this Australian graph correctly. (If they make graphs differently in Australia, I give up on this hemisphere business.)
I guess it makes sense that the physical end of the world would exhibit end-of-the-world behavior. This is what we get for being roughly spherical. If we were flat, the end of the world would have an edge, a big wall or a waterfall or something. Instead, we’ve got a place where there’s only one day a year. Two places, actually. The reverse is evidently happening at the North Pole, which might be why Santa gets out of there every year around the solstice. Guy needs a break.
I still can’t comprehend it, though. I’m trying to picture the spinning globe doing its tilts and rotation and all that and I’m just….oh wait. I think I maybe get it. So when the equinox is happening and Earth’s straight up and down, the North and South Pole are getting half light. Once it tips one way, though, one pole gets dark, and once Earth passes the straight-up-and-down orientation going the other way, that pole gets light again. The earth keeps spinning, but at some height—which varies by how tilted the globe is—it starts becoming 24-hours light and dark. How far from the pole that point is depends on the degree of the tilt. (Also, this now explains why the NASA post kept mentioning that the Arctic and Antarctic Circles are the furthest north/south lines where at some point in the year, there’s a 24-hour day.)
I’m trying to find a video that shows this in cartoon form, but they all get hung up on technicalities. The Earth doesn’t actually tilt back and forth, for example. That phenomenon’s a product of the globe’s rotation. We’re in over our head, guys. Someone go find a good video and please bring it back.
It’s light at the South Pole right now, though. They’re about three and a half months into their day.
UPDATE! Found a video. Start this at 2:42. You can stop watching at 4:20.
