Neil deGrasse Tyson Explains the REAL Length of Day

A day is 24 hours, right? Right?!?! On this StarTalk explainer, Neil deGrasse Tyson and comic co-host Chuck Nice investigate the length of a day.

To start, Neil explains why a “sidereal day” is 23 hours, 56 minutes, and 4 seconds and a “solar day” is, on average, 24 hours. You’ll learn why Earth’s orbit around the sun impacts how we measure the length of the day. Should we re-define the length of a second? Discover more about leap seconds and how we decide when to add them to the calendar.

Find out more about atomic clocks and sun dials. Neil explains why the Earth is slowing down and why the Moon is spiraling away from us. We also discuss how tides serve as a counter-balance to the Earth’s rotation. All that, plus, we explore the many things that can impact Earth’s rotation including seasonal animal migrations, earthquakes, melting land glaciers, and more!

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About StarTalk:
Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!

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0:00 - Introduction
0:54 - How Long Earth Takes To Rotate
3:33 - Earth’s Orbit Around The Sun
5:25 - The Most Accurate Timekeepers
7:33 - Earth Is Slowing Down
11:45 - What Increases The Speed Of Earth’s Rotation?
13:45 - Neil’s Diabolical Idea
14:44 - The REAL Length Of A Day
15:54 - Closing Notes

[STONEDECISION]

I don’t know. The real length of day depends on who you spend it with.

[ImSkittzle]

Just knowing there are experts who devote their lives to observing this information. Absolutely mind blowing, tremendous respect for scientists.

[strandednseattle]

One thing I love about Dr.Tyson is that he is true to self. The friendly and warm person he is on video is the same he is in person. I had the privilege of meeting him a few years back in Austin at the Long Center.

[mettyowino]

I'm from Kenya and l like Neil degrease passion for science .I'm on my information technology degree and l want to devote my life to what I do just like Neil.

[MSeaNP]

I'm trying to get my 15-year-old niece in Nepal to watch these explainer videos. And despite having a beginner English vocabulary, she's extremely talented and now continues to be fascinated with what Tyson's scientific mind has to say since being introduced to A Space Time Odyssey. Let me tell you, not many are aware of his brilliant mind here in my country, and I'm glad I was able to inspire a young talent to learn from such a brilliant person. I hope even these explainer videos will be more simpler to understand for someone with a limited capabilities in the English language so that she can continue to be inspired. Thank you Neil.

[CZinDC]

Chuck is so lucky. He basically got paid to get an education from Dr. Tyson. Love the show!

[davidwright]

We're lucky to have Chuck. He adds the whole premise to the show. Science plus comedy. Plus he knows his stuff too.

[rupertwressell]

2:50: "I've only just begun" sums up Neil perfectly 🤣

[mariuszkochel]

Neil: "The Earth is slowing down."
Chuck: "Well... u know... it's kinda old."
XD

[mef]

I’m old enough to remember when there was a phone number to call to get the time. “At the sound of the tone the time will be 6:30 and 24 seconds...beeep”

[ymvoqln]

I can't imagine how hard it is to find a guy that understands these very unorthodox topics and explain then very simply and a guy who isn't trying to steal the show or act smart. But is genuinely interested and ads character to the show. Absolutely brilliant but I have never expected less from dr.Tyson

[MakeLifeExtraordinary]

Neil, , I could have a never ending conversation with you. Thank you for everything you do.

[LaibaStarXX]

This is the real way everyone should be educated!😌

[dumaskhan]

"You don't tell time, time tells you" George Carlin.

[ArtKeshav]

Chuck made a classic move at 02:16. Yawned with a closed mouth so that the teacher won't be able to catch you 😏.

[positivevibrations]

Chuck is the very best natural comic relief, kind-hearted, open-minded, genuine student to Neil's lessons.
Keep it up, Chuck. :)

[kayanims]

This actually makes sense. I always wandered why we needed to reset analog clocks in the past. I always thought it was a problem with the batteries

[Jager-ervc]

Neil: “I’m gonna talk about Earth”
Chuck: “I like that place.”
Me: “Me too.”
(Love me some StarTalk!)

[thereviewguy]

So glad I found this channel and subscribed. I miss science class 5th grade. Was a blast.

[williamlubak]

The combination of Neil and Chuck is magic.