# Longest and shortest solar day? **URL:** \ **Category:** Factual Questions\ **Created:** [January 3, 2024, 10:42pm UTC](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569 "2024-01-03T22:42:24Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 4, 2024, 11:04pm UTC](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569/21 "2024-01-04T23:04:19Z")
In case anyone’s wondering about all this talk of “analemmas”: At any given moment, there’s some point on the Earth where the Sun is directly overhead. If you start at some moment, and mark that point on a globe, and then wait exactly 24 hours, it’ll now be a slightly different spot where it’s directly overhead. Continue that way, marking the location every 24 hours, and over the course of the year, those sun-points will trace out a figure 8 shape. That’s what that shape on the globe is. You could put it at any longitude, depending on what moment you chose as your starting point, but globe-makers usually put it somewhere in the Pacific Ocean (along with the manufacturer’s logo, and a legend of symbols, and so on), because there’s a whole lot of nothing there. I wrote a program years back to generate analemmas, given axial tilt, eccentricity of orbit, and so on. I ought to dig that up, and see if I can get it to work again. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [January 5, 2024, 1:10am UTC](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569/22 "2024-01-05T01:10:29Z")
> [@Chronos](#): > > I wrote a program years back to generate analemmas, given axial tilt, eccentricity of orbit, and so on. I ought to dig that up, and see if I can get it to work again. > **[Analemma Calculator](https://mtirado.com/resources/analemma-calc/)** > > Interactive Analemma plotter ---
**Author:** ![Freddy\_the\_Pig](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Freddy\_the\_Pig](https://boards.straightdope.com/u/Freddy_the_Pig)\ **Post date:** [January 5, 2024, 4:15am UTC](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569/23 "2024-01-05T04:15:55Z")
> [@Yelnick\_McWawa](#): > > When you look at an analemma, the northern loop is skinnier than the southern loop. I wonder what it looked like 700 years ago when the perihelion coincided with the winter solstice. You would have had an even smaller and skinnier northern loop and a fatter and taller southern loop. > [@Yelnick\_McWawa](#): > > What will it look like in 5000 years when perihelion coincides with the vernal equinox? Two symmetric loops, intermediate in width between the present-day loops. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [January 11, 2024, 12:19am UTC](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569/24 "2024-01-11T00:19:45Z")
I remember reading about a guy who took a photo of the sun every clear day for a year, exactly at noon (ignoring DST), not changing the film (in the days when photos were on film). Even though there were gaps from cloudy days, the images traced an analemma. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 11, 2024, 10:31am UTC](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569/25 "2024-01-11T10:31:43Z")
Dennis di Cicco, Exposing the Analemma, Sky & Telescope, June 1979, p.536–540. [Previous page](https://boards.straightdope.com/t/longest-and-shortest-solar-day/995569.md?page=1)