You can blame Tam at View From the Porch for leading me to this. I saw her celebrating the solstice in this morning's post and was struck with empathy for any one who gets Seasonal Affective Disorder living "up north" and my own rather different reaction to the solstice.
Solstice, of course, comes from words meaning "sun" and "standing still" and marks the time when the sun's position stops moving south (today) or north (June's summer solstice) for a moment before starting to move in the other direction. Tam was celebrating today because the sun has stopped moving south and is starting back north, leading slowly but inexorably to a longer daylight portion of the 24 hours. Which is the part I tend to dread. Not that I hate daylight, but this is Florida and my chances of being comfortable in the summer aren't as good as during the other 3/4 of the year. "If I've said it once, I've said it a million times" a technologically advanced civilization couldn't exist here without air conditioning.
That says that from my viewpoint, both the summer and winter solstices have something in common: I'm hoping for cooler weather.
According to Time And Date (dot com!), the moment of the sun standing still was 10:03AM Eastern Time here, or 1503 UTC. It's the shortest day of the year but neither the latest sunrise or the earliest sunset. The earliest sunset was in early December; the latest sunrise will be in early January. According to the Sunrise and Fall app on my phone, sunrise this morning was 7:10 AM and sunset 5:31 PM.
The motion of the sun north and south over the course of the year traces out a
curve called an
analemma, which you usually see printed on globes. You can photograph one of
these yourself if you care to dedicate a camera to doing nothing else for a
year. It takes a bit of planning, but you just need to take a
photograph at the exact same time (use UTC so you don't get messed up DST
chances) from a camera left at the exact same place throughout the year and be
sure before you start that the image will fit on the film or sensor.
Once a week is a good, round number and you pretty much can't make the exposures
too short. Take the photograph when the sun is high enough above the
horizon to record on the winter solstice, and leave the camera pointed at the
same place for a year. Add one longer exposure picture when the sky has
a pretty look you like and maybe you can get a picture as pretty as this one,
taken by István Mátis from a window in his apartment in Romania. He
wrote,
The discs of the Sun are taken between 11/6/2012 and 1/19/2014 at 7:00 UT, which is 9'o clock in the morning local time during winter and 10'o clock during daylight saving time. The background is made on 1/14/2014 at 7:55 local time, from the original location of the analemma.My guess is that the gaps in the pattern were caused by cloudy days.
Of course today also has another important meaning that was mentioned last Thursday. It's the 10th anniversary of the first successful landing of a Falcon 9, December 21, 2015. While I vividly remember standing outside watching everything visible about the launch, the landing was below our visual horizon so we couldn't see it that night. SpaceX released this video some time later.
The pure emotion of everyone working the launch is awesome to see.
One thing that has struck me with moving out to the semi-rural is that the sun really does essentially *stop*.
ReplyDeleteThe view to my NE has a house about 800' away. It doesn't subtend much of an angle but this time of year the sun rises over it for about a month.
It's one thing to know the math and why things do the things they do, it's quite another to actually see it happening in real life.
I can see it becoming important to prehistorical peoples, and I imagine that it took a lot of work over years to accurately resolve the actual stopping point in the very slow changes.
RE 7:10AM: My know-it-all Golf Ball AI told me sunrise sunday was at 7:23AM Central. Silly me, I was unconsciously thinking our time zones would have a sunrise time difference of one UTC hour. The bloody AIs must use our longitude. Lessee, one degree per four minutes of time puts you... nevermind, I'd have to take off my socks to keep counting and my toes are cold.
ReplyDeleteThe time zones were originally created to keep noon when the sun went through the meridian - and overhead if you lived where the sun made it there. The biggest difference in times for sunrise/sunset should be how far east or west you are in the time zone. But then the edges of the time zones got moved from constant longitude north/south for convenience. We're closer to the eastern edge of eastern time than to the border with the central time, so I expect it to be earlier in the hour here.
DeleteHope that makes sense!