Why are there two tides a day? - Elise Cutts

Dig into how the Sun and Moon are responsible for the tides on Earth, and what this force looks like on other celestial bodies.

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In the 17th century, Isaac Newton offered the first gravitational explanation of tides. As he correctly identified, tides are choreographed by the motions of celestial objects, and Earth’s tides in particular are mostly driven by the Moon. But the precise nature of this relationship is actually quite nuanced. Elise Cutts explains how the Sun and Moon are responsible for the tides.

Lesson by Elise Cutts, directed by Rémi Cans, Atypicalist.

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Thank you so much to our patrons for your support! Without you this video would not be possible! Nevin Spoljaric, Sid Chanpuriya, Anoop Varghese, David Yastremski, Noah Webb, Roberto Chena, Oliver Koo, Luke Pisano, Andrea Gordon, Aleksandar Donev, Nicole Klau Ibarra, Jesse Lira, Ezekiel Raui, Petr Vacek, Dennis, Olivia Fu, Kari Teffeau, Cindy Lai, Rajath Durgada Manjunath, Dan Nguyen, Chin Beng Tan, Tom Boman, Karen Warner, Iryna Panasiuk, Aaron Torres, Eric Braun, Sonja Worzewski, Michael Clement, Adam Berry, Ghaith Tarawneh, Nathan Milford, Tomas Beckett, Alice Ice, Eric Berman, Kurt Paolo Sevillano, Jennifer Heald, Megulo Abebe, isolwi, Kate Sem, Ujjwal Dasu, Angel Alberici, Minh Quan Dinh, Sylvain, Terran Gimpel, Talia Sari, Katie McDowell, Allen, Mahina Knuckles, Charmaine Hanson, and Thawsitt.

[lifeartandall]

4:55 Before you worry, the sun will have already gone and taken the earth with it before the earth stops rotating. This is very comforting, thanks 😅.

[LegoJJ]

I would like to say whoever worked on this animation did an incredible job 👍👏👏

[remicans]

It was a pleasure directing this Lesson, which will most likely be my last.

I hope you all enjoy watching it, and appreciates the effort which my team and I put into making this complex knowledge more easily understandable and accessible to everyone. With a very cool artistic direction, a smooth animation work, and a very effectively immersive soundwork. 😊

[gabrielas]

For some reason, the metaphor of the child and the carousel with his hair blowing in the wind almost brought me to tears. How beautiful when a metaphor elicits such emotion.

[JakeJackson-fnl]

Thank you Ted-Ed for this flawless representation of *"Why we have two tides a day?"* A tricky question which was perfectly answered in the year *CE 1687* by Sir Isaac Newton in his Philosophiæ Naturalis Principia Mathematica.

Any mention of superfluous statements about the complexities regarding tidal variations at particular locations around our global waters, including the *Gulf of Mexico* and during different phrases of the moon.

Are all surplus to requirements and belay the true underlying message we should all take from your excellent and correct presentation: *That all tides are caused by the inertial motion of our oceans, on a shared planet, in orbital motion around a shared centre of mass.*

Thank you kindly.

[keziagreste]

This reminded me of a childhood trip to a beach. The water was nowhere near the shore, so I remember walking almost 2 kms ahead just to find it. I watched as it slowly crept forward, inch by inch, eventually making the beach feel whole again.. only to retreat once more. I didn’t know anything about tides back then, so I probably thought it was some kind of magic. Realising now that it was low tide.. and honestly, I think it’s even more impressive than high tide.

[oortcloud]

As Professor Carl Sagan once said so eloquently about the Pale Blue Dot.
*_"To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish the pale blue dot, the only home we've ever known."_*
Thank you Carl. 😌 *To live in the hearts we leave behind is to live forever.* Enjoy life and remain curious.

[oortcloud]

After watching ten million tidal explanations on the physics of inertia and gravity behind our daily tides. I realised this is the clearest and best explanation of the tidal phenomena that everyone can understand. Thank you, it was a delight to view and the presentation was excellent. Many, who live far inland, never get to experience the full force and majesty of the ocean, but we should all be aware of it presence and the effect it can have on our daily lives.

[wavydaveyparker]

This is one of the best tidal explanation that's ever graced this sharing platform.

You know we find it extremely fascinating that no one has mentioned the equivalence principle, or freefall motion in a non-uniform gravitational field, or the methodology behind using a non-inertial frame of reference.

The story behind our understanding of Gravitation is a fascinating adventure, which was partially solved by Sir Isaac Newton over three hundred years ago, and later revised by Albert Einstein and James Clerk Maxwell at the beginning of the twentieth century.

Although, with the recent detection of gravitational waves and the enormous blackholes in our accelerating universe. We may need to revise our general theory once again to incorporate it into a unified theory of everything. There you go, that's our next assignment and we expect to explain everything as superbly as this in under five minutes.

[TheHotshott]

I vaguely knew how tides worked, but I must say this kind of broke my brain and is incredibly fascinating.

[quietseawaves]

I love the music and art style. I felt like I was listening to some old forgotten legend... I really like it.

[jgonascar]

Tide goes in, tide goes out. Never a miscommunication.

[saranegrete]

Gracias a los videos de Ted Ed, he mejorado muchísimo mi audición. Los amo ❤

[maleeshapriyanjana]

This is the best video that described how tides are formed in opposite side of earth

[wavydaveyparker]

Opening with a reference to tragedy that befell the army of Alexander the Great is a truly inspirational beginning to a wonderful explanation for our relentless tides. We all know that a *Knot* is a unit of speed equivalent to one nautical mile per hour. Although, were you also aware of how significant a single *Knot* would be in the life of Alexander.

Whoever shall solve the *Gordian Knot* will become ruler of Asia. Of course Alexander wasn't very good with knots and decided to cut it with his sword instead. Prophecy was therefore fulfilled and the rest is history. Congratulations Ted-Ed, you just unravelled the knotty tides and will continue to share inspiring knowledge with the world.

[chribu_]

I didn't know this. Thanks for teaching me something new in such a beautiful way!

[SnehaSharma-nbtj]

I know this background music is from Google's Lunar moon game. 3:01 Btw, Ted Ed animations are getting meticulously Better day by day!❤

[Murdaking]

Alexandra you’re so so good at narrating, the way you talk is so easy on the ears. It’s exactly how I like to hear a narration ❤️‍🔥

[cybermonkeys]

BCE = *Before the Common Era.*
It's often used as an alternative for the term,
BC = _"Before Christ"_
As a way of referring to years before year one in the Gregorian calendar. It's a more secular way of referring to years before the year one.
Both uses are fine and it took me precisely two seconds to acquire that knowledge. Unlike the hundreds of years, which humankind has spent trying to understand the phenomena of tidal formation, which was beautifully explained in this short presentation.
Thank you Ted-Ed.

[MilevaRuben]

"Çünkü hiçbir iki ardışık gün kıyı şeridi tam olarak aynı değildir. Gelgitler sadece sonsuz ritimlerinde ilerlemek ve geri çekilmekle kalmaz, aynı zamanda denizin seviyesi de asla durmaz."
Rachel Carson, The Edge of the Sea.