The Equation of Time: Clocks Vs Sundials

A few centuries ago, the arbiter of "local noon" wasn't the mechanical clock, it was the sundial. The pseudoscientific-sounding "equation of time" is how you convert between the two -- and perhaps not the way you'd expect.

[RobMacKendrick]

I grew up with an 18th century Japanese clock that kept solar time. It also had just one hand and a system of chimes that was just as complex as the clockwork that sounded them. (We never did figure out what they were telling us.)

[KiloOscarZulu]

"earth is tilted because of the seasons" - it's the other way around, there are seasons because the earth is tilted.

[Tititesouris]

I don't really see the point of sundials in Britain anyway. :P

[RyanHannaMusic]

i like how you guys call it 'things you might not know' as opposed to thinking i already didnt know...but the difference in you guys and the others is that you tell me things i actually didnt know. fair play lads

[pmyou]

This is the most interesting reality check that has come my way in ages! The consequence of technology are subtle and amazing. You fleshed out this story with lots of detail that I really did not know nor even imagine. Thank you.

[DaltonHBrown]

I like that the series name is "things you MIGHT not know" as opposed to "Things you didn't know"

[BastuGubbar]

it's always nice when you run into a rare tom scott video.

[wmgthilgen]

The clocks in the new tower in Dubai are set a slightly different times depending on which floor. One has to pray at exactly sun down which because of it height, occurs at different times.

[mariusloubeeka]

What a planning fail to put the sundial where it can't be used the whole year.

[Kae-Lexi]

I can't believe this
Tom found sun in britain

[lewistrundell]

Love how there are videos from Tom that I still haven’t seen

[ThreeXcore]

I've been watching your videos for about 3 hours straight... I can't get enough ! Thanks for your time and stay healthy !! :)

[malup]

I remember visiting a sundial in Jaipur and it was breathtaking. Someone built a sundial that was accurate for every 2 seconds. It was humongous and absolutely crazy.

[sydhenderson]

An analemma shows both the declination of the Sun (the angular distance it is from the celestial equator. and the amount of time you have to adjust. That's the figure 8 you often see on globes. One lobe is bigger because the Earth's orbit is elliptical.

[independent]

*clouds cover the sky *
Scientists of the olden times: no! The atomic clock has broken!

[MrMartinSchou]

Depending on where you look, the sun rises earlier in the western part of the country than in the eastern part.

If the country is long enough in the north/south direction that is.

For example - I currently live in Stockholm (18°15'E) and today the sun rose at 3:30 AM. In Ljusdal (16°05′E) the sun rose at 3:07 AM. That's 23 minutes earlier, despite being further west than Stockholm.

This diminishes as you move further south though, but it's still there. For example, today the sun rose in Grigadale (the westernmost settlement of mainland Britain - W6°11') at 4:32 AM and in Dover (E 1°18') at 4:39 AM.

[peterpesch]

Makes me think of the sundials (1 for each half of the year) we used to have at our university in Nijmegen.
They told the time plus the (approximate) date (provided you new which half year you were in).

[evilpandakillabzonattkoccu]

We have a sundial just like this at our local park. The kids just run over it, unnoticing. I cant help but stand on it every time we go. I love it

[FuncleChuck]

I love watching the old ones. Time hasn’t harmed the content.

I would love to see the End of DST happen this decade.

[sbrazenor]

I ended up watching this video with the song 'Needing / Getting from OK Go in the background. It synced perfectly and was actually pretty funny to watch. LOL :) I ended up muting the sound and tweaking the time positions, but I was able to get a perfect sync between movement. It looked like Tom was dancing to it, and singing along. LOL :)