How eclipses proved that the Earth is slowing down

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Without eclipses, our world would be a lot different because eclipses give us the ability to do science we otherwise wouldn’t be able to.

LEARN MORE
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To learn more about this topic, start your googling with these keywords:
- Corona: the outermost part of the Sun's atmosphere.
- General Relativity: a theory of gravitation developed by Albert Einstein that says that the observed gravitational effect between masses results from their warping of spacetime.
- Lunar Eclipse: an eclipse in which the moon appears darkened as it passes into the earth's shadow.
- Solar Eclipse : an eclipse in which the sun is obscured by the moon.
- Tidal Friction: strain produced in a celestial body (such as the Earth or Moon) that undergoes cyclic variations in gravitational attraction as it orbits, or is orbited by, a second body.

CREDITS
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Cameron Duke | Script Writer, Narrator and Director
Sarah Berman | Illustration, Video Editing and Animation
Nathaniel Schroeder | Music

MinuteEarth is produced by Neptune Studios LLC

OTHER CREDITS
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Photo of 1919 Total Solar Eclipse
Credit: ESO/Landessternwarte Heidelberg-Königstuhl/F. W. Dyson, A. S. Eddington, & C. Davidson

OUR STAFF
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Lizah van der Aart • Sarah Berman • Cameron Duke
Arcadi Garcia i Rius • David Goldenberg • Melissa Hayes
Alex Reich • Henry Reich • Peter Reich
Ever Salazar • Leonardo Souza • Kate Yoshida

OUR LINKS
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REFERENCES
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Littmann, Mark, and Fred Espenak. Totality : The Great American Eclipses of 2017 and 2024. Oxford, United Kingdom, Oxford University Press, 2017

Steel, Duncan. Eclipse : The Celestial Phenomenon That Changed the Course of History. London, Headline Book Pub, 1999.

[davidtitanium]

i just made the connection that helium is named after the sun (helios) because it's first discovered on the sun

[Finkelthusiast]

Absolutely amazing that Helium was first observed on the Sun before it was found on Earth.

[PlanetAstronox]

I always thought the most remarkable thing about solar eclipses on Earth is that the moon and sun, coincidentally, have roughly the same apparent size in the sky. Equally by coincidence, humans are around to see the spectacular eclipses made possible by this, since the moon was closer in the past and is drifting further away.

There very well may not be another planet in the entire galaxy where you can see eclipses like ours from the surface of a planet.

Edit: Looks like the sister channel MintePhysics has a video going into much more detail about this

[babilon]

Wow! I knew eclipses were good for studying the sun. But having it tell us something about the earth? And using ancient measurements to effectively conduct a millenia-long experiment?

No pun from me today. I'm astounded.

[Naidnapurugavihs]

Excellent work as always! It is fun to learn an astronomical amount of information on several different topics from the research and record of a single event! 🌎🌎❤❤

[semipenguin]

I used to live in Athens, Tennessee. In 2017, I got to see the Great American Eclipse, as totality passed through our small town. It was awesome.

[thebeautyofuniverse]

Just wow, it’s fascinating how capable ancestors in the past were to track it

[ethribin]

The deeper you delve into it, the more do you realuze just how much the moon has done for humans and life on earth.
And considering how unusual and rare this kind of size ratio between planet and its satelite is, the moon might actually be one of the major factors (together with water, temperatures that allows all 3 states of water on the planet and a strong magnetosphere) that has allowed life to appear on earth.

[julianaylor]

I don't know if you'd ever seen the old British horror/science fiction black and white film, The Day The Earth Caught Fire. In the film, the first sign that something had happened, was a solar eclipse that happens too soon. In the film's story that meant that the Earth had been knocked off its axis and out of its orbit, moving towards the Sun. That was caused by two simultaneously enormous nuclear tests. The plot used that astronomical event as its start point and then introduced all the meteorological events, realistically, as known to science, when the film was made.

[mrdraw]

Does this eclipse analysis take into account the Moon receding from the Earth? It's currently receding at a rate of about 4 cm per year, so its orbit increases by about 12 cm per year. This alone would increase its orbital period by about 1/10.000 second, given its orbital speed of about 1 km per second. Over time, these tiny bits add up, so the Moon's position could change quite a bit as a result.

[Terrinist]

slow rotation of earth = more hours = MORE FREAKING SCHOOL 😭😭

[runnergo]

There's a pretty good 2008 movie called Einstein and Eddington that shows what Eddington went through to take that eclipse photograph to prove Einstein's theory of relativity was correct. The things devoted scientists will go through is absolutely amazing.

[MaxArceus]

I prefer the old thumbnail and title, about why the earth is slowing down, with the nice drawing.
Youtube stats will say I clicked on this with the new thumbnail, making you think "Ah, updating the thumbnail worked!', but in my single datapoint case, it didn't. I simply hadn't gotten around to it yet.

[joshuaespinoza]

2:07
"on a lighter note"
I bet that flew over some people's heads

[MasterHigure]

22:05 Unless you care about sub-meter precision, GPS functions just fine without taking relativity into account. It would drift about 15cm per day, and even from the start of the project, the satellites got weekly updates.

It is common to claim the drift would be closer to 10km per day, but that ignores a fundamental part of how GPS works: it measures the time difference between satellite signals, not the absolute arrival time. If they are all delayed the same amount, the fact that they come 10km later is irrelevant.

What does happen, though, is that the internal orbit calculation of the satellites become wrong as they have an incorrect clock, so they aren't where they think they are when they send their signal. And this error would increase by about 15cm per day.

[rickseiden]

I live right in the middle of the April 2024 eclipse. I have my glasses and I can't wait!

[mwm]

I’m in Mississippi. I want to bring the family to the April eclipse, where should I go? What are some good places?

[justincronkright]

Recreating different phainomena that existed in the past, but are far less likely now or could exist in the future (although the past's greater energy density is more fun) should be done a lot more than just on science fiction programmes!

[davidpacheco]

For those interested, there's a movie that was made around the proving of Einstein's relativity theory (the experiment mentioned in the video where photos were taken of the sky while there was an eclipse happening and while there was not), which explains the specifics much more in detail than our darlings at Minute Earth can in a 4 minute video. The movie is called "Einstein & Eddington" and is currently on HBO, I believe

[Alex-jslg]

"Retrodict" - I learned a new word today.