Equation of Time

The equation of time describes how the difference between the "natural time" kept by a sundial changes over the year, due to the changing length of the solar day.

[@paulgo51]

I was one of those who had a hard time visualizing the effect of the earth's tilted axis. With the animation showing the view from above earth's north pole I finally got it. Thanks for the great explanation.

[@narayanannavaneetham1931]

same

[@jinks908]

You are so clear and concise that I don't even feel like I'm learning, I feel like you're uploading and installing information onto my brain without me having to do anything lol. You are a fantastic teacher, man.

[@ExplainingScience]

Thanks for your great comment. I’m really glad you liked the video. As you enjoyed this one, you may want to look at some more of the videos on kzbin.info or subscribe to the channel As we say in England Cheers !!!

[@KennethPartridge]

I have been struggling for years to visualize the tilt component. Thank you for this video!

[@DrummerTeeJay]

I stumbled upon your web page and read your explanation and watched the video presentation. Well done! I did not know about the Earth's tilt also contributing to the length of a day throughout the year. Thank you for your fine work.

[@ExplainingScience]

Thank you

[@lemuelbecc]

Splendid video. Well organized and demonstrated.

[@ExplainingScience]

Thank you

[@kaisunra9676]

Explaining the effect of obliquity in terms rate of change in right ascension really cleared up a lot. Your celestial sphere visualization also makes it much easier to fully conceptualize the analemma which can be a struggle

[@ExplainingScience]

thank you

[@KipIngram]

Excellent. I've watched several of these, and they all explained what the results were and how to correct your sundial time. But this is the first I found that actually ties it to orbital dynamics in a clear and completely understandable way. I particularly like your two graphs at the end, where you sort of hit the "function and its derivative" in a nice intuitive way. You covered it very nicely - thanks.

[@ExplainingScience]

Thank you

[@pinja.leppaaho]

I have been trying to understand this concept for a while now and this cleared it up a bit! Thank you

[@N_0706]

Thank you very much for this video. The effect of Earth's tilted axis was pretty difficult for me to visualize but this video made all my concepts clear!

[@morewealth23]

Amazing explanation. Thank you so much. Your channel deserves way more subscribers. Please keep up the good work.

[@ExplainingScience]

Thank you very much for your kind comments. Please spread the word about my channel by recommending to your friends

[@DownhillAllTheWay]

@@ExplainingScience I came across your channel because my grandson (7 years old) has been given an asignment to make a sundial (as well as the other children in his class, of course). The sundial could be a simple as a stick in the sand, but it's an opportunity to teach him a bit more about how the heavens work. I won't go into the detail you presented here (he's 7!), but I will be able to give him a little more than most of his class will be learning. They say that nothing succeeds as much as success, so making him feel a little superior is no bad thing.

[@ExplainingScience]

Thank you

[@비든라인]

I wanted to know equation of time, then I found your video. It was helpful. THANK YOU SO MUCH!!!!!

[@ExplainingScience]

Thanks for your nice comment. I’m really glad you enjoyed the video. You may want to look at some more of the videos on kzbin.info or subscribe to the channel.

[@DownhillAllTheWay]

If you have an accurate timepiece that can be used to check the sundial, its errors could be known. Then mathematicians could play around, trying one formula after another to work out why this difference in the solar day length happens - but this was all worked out before such accurate timepieces existed. I have no idea how those ancient mathematicians and astronomers did it - but HUGE respect to them!

[@jonburrows]

"I have no idea how those ancient mathematicians and astronomers did it"--this is *precisely* the question that brought me to this video in the first place. I want to know!

[@DownhillAllTheWay]

@@jonburrows It is explained in this video that the errors in the sundial are due to the speed of the earth past the sun, due to its orbit being elliptical, not circular. I'm not much of a history buff, but I know that sundials have been around for a long time (since 1500 BC, I just found). When it was first discovered that they produce errors, was it known at that point that the earth had an elliptical orbit around the sun? Kepler discovered the elliptical orbit in the 17th century, but I don't know when (or HOW!) it was known that there are errors in the timekeeping of a sundial.

[@PaleBlueDott]

Well, I'm assuming that they were able to figure it out by looking at the constellations. They noticed that the sun "moves" eastward through the year, moving from constellation to constellation. So they must have realized that the time it takes for it to rise at its highest each day is affected by this apparent eastwards motion. After that, they probably attempted to trace the rate/speed of this motion at different parts of the year, realizing that the sun "moves" eastward more/less at different parts of the year, correlating those changes of speed to the errors on the sundial. I doubt they ever understood exactly why that was. They just knew that when the sun "moved" eastwards more in a particular span of weeks/months, it took longer for it to reach the zenith, therefore the sundial "lagged behind". The opposite happened when the sun "moved" eastwards less in a particular span of weeks/months. The sun rose faster and the sundial caught up or even surpassed the "mean" time.

[@libregisin9878]

Thank you for your excellent explanation. For me it was very clear and answer some of my questions about solar time. For example, it explains why the Sun sinks the evening the earliest about 13th of December, but rises the morning the latest about the 4th of January.

[@ExplainingScience]

Thank you Libre Glad it was helpful! Please recomend Explaining Science to your friends and acquaintances

[@deanemilne6275]

nicely explained in detail with clear graphics

[@LaVaProductions]

Great explanation. Makes it easier to understand. But why do we have every 4 years a February 29? I might have missed it in your video

[@PaleBlueDott]

I'm assuming this is the reason analemmas have a figure 8 shape and not a straight line.

[@bill8784]

If navigating at sea using a sextant at noon to work out one’s longitude, presumably one needs a table of some sort to adjust for the effect of the equation of time?

[@simrethdhingra4409]

hey, thank you so much for a fantastic video just wondering how you found the 'total' at 9:17 if you were only using excel it would be a helpful skill to be able to use. I don't expect a reply but would really appreciate one. from anyone

[@simrethdhingra4409]

BTW i shared ur video

[@chipnole]

Thanks for the explanation, its still challenging to comprehend,

[@LiveHappy76]

Yeah, I'm struggling after a very thorough, slow listening with pauses and replays...lol.

[@ExplainingScience]

Thanks for your nice comment. I’m really glad you enjoyed the video. You may want to look at some more of the videos on kzbin.info or subscribe to the channel.

[@Eyotuber]

I'm not astronomer, but im curious why longer daylight in the summer. I think longer days are not related to the speed rate of axis shift but to intersection of ecliptic forming the declination with the equator along the same longitude where these north latitude experience delay, so tilt axis causes seasons and daylights.

[@dylanjj]

Excellent video

[@francescodoenz]

OUTSTANDING!

[@ExplainingScience]

Thanks for your nice comment. I’m really glad you enjoyed the video. You may want to look at some more of the videos on kzbin.info or subscribe to the channel.

[@10-AMPM-01]

1:24- So "Colored People Time" was an artifact of time keeping knowledge? Well, that's about the same as "uninformed investor" today.

[@grahamparsons4242]

Thanks

[@christophesutter1844]

Pourquoi vous ne dites pas la vérité sur le système solaire que c est le soleil qui tourne autour de la terre c est ce qui explique l analemm de mars entre autre.merci

[@REALStinkyCash]

What scientific experiment proved that this is the only possible scenario to explain the observed phenomenon?

[@discovertheworldwithrio7836]

There is no Globe 👁️

[@EmersumBiggins]

Stop using the globe map then?

[@phyarth8082]

5:16 Celestial Sphere - IMAGINARY sphere centered on Earth. Sun rotates around stationary Earth in a heliocentric model :/ ? Blatant lies of Sun rotation with 23.5 degrees. We live inside concave stationary earth where the sun rotates 24 hours per day and tills 23.5 degrees back - tropics of cancer and forth - tropics Capricorn that gives seasons. Heliocentrism and Sun rotate around stationary convex Earth with tilt which is again an insult to human intellect.

[@N_0706]

Lol seems like you didn't understand

[@nickinskeep]

I wanna smoke what you're smoking

[@VideoNash]

thanks