00:00You know, we've all begged for just one extra hour in the day.
00:05Actually, two hours would be better.
00:07Well, scientists have good news and bad news.
00:10The good news is that our planet is heading toward a future where a day could last 25 hours.
00:16The bad news is that eventually, the same physics that makes the day longer will also get rid of our
00:21planet's rotation,
00:23literally freezing Earth in time.
00:25Meaning, endless days and nights and oceans fleeing to the poles,
00:30all while the atmosphere turns into a relentless planet-wide storm.
00:34Uh-oh.
00:36Now, back when the Earth was just a massive, messy cloud of dust and gas,
00:41gravity started pulling everything toward the center.
00:44As all that debris smashed together, it started to swirl like water rushing down a drain but on a cosmic
00:51scale.
00:51That spin caused a momentum.
00:53Since space is a vacuum, there was no air to slow us down.
00:58Earth just kept spinning, and that spin became a day.
01:02One full rotation takes about 24 hours.
01:05And that's the rhythm we've known since we started recording time.
01:09But the thing is, we adopted 24 hours as a close estimate.
01:14In truth, a day is never exactly 24 hours long.
01:18Now, basically, Earth keeps spinning, but it's constantly losing tiny bits of speed.
01:24That's mostly because mass keeps moving around.
01:27Think of it like a figure skater.
01:29If they pull their arms in, they speed up.
01:32If they put them out, they slow down.
01:34Earth does the same thing, except without arms.
01:37When the 2011 earthquake hit Japan, it shifted the ocean floor so violently that it pulled Earth's mass inward,
01:46instantly shorting our day by 1.8 microseconds.
01:50Conversely, as glaciers melt and water rushes from the poles to the equator,
01:55Earth's arms are spreading out, causing us to drag.
01:59We're not just sitting on a big rock.
02:01It's like we're on a wobbly, spinning top that moves every time something heavy happens on it.
02:07Most days end up being a few milliseconds longer than 24 hours.
02:12We can't feel this, but atomic clocks can measure it.
02:16Over long periods of time, those milliseconds add up.
02:19And as they do, the length of a day slowly increases.
02:23That's how a 24-hour day starts drifting toward 25.
02:27To check this, scientists pulled together nearly 3,000 years of sky records.
02:33Thousands of years ago, people carefully recorded eclipses.
02:37It was a scary event.
02:39Kings, priests, and astronomers wrote the exact time and location when the sun vanished.
02:44Those records survived on clay tablets, scrolls, and manuscripts.
02:49For the sky to go dark, the sun, Earth, and moon must line up perfectly.
02:54If the timing is off by even a second, the shadow falls on the wrong part of the world.
03:00Today, astronomers know the moon's movements with incredible precision.
03:04They actually bounce lasers off mirrors left on the lunar surface to measure its orbit.
03:09That's why, in theory, we should be able to rewind the past like in a YouTube video
03:15and see every ancient eclipse exactly where history records it.
03:19But when scientists tried that, the moon showed up too early.
03:24Or too late.
03:25The shadow wasn't where the record said it should be.
03:28The puzzle only solves itself when you realize one thing.
03:31Earth used to be a little faster.
03:34When researchers adjust Earth's rotation to be slightly quicker, everything snaps into place.
03:40In other words, Earth was spinning a little faster in the past, and these eclipse records show it.
03:46On average, this translates to a day increasing by about 1 to 2 milliseconds every 100 years.
03:53That's a thousandth of a second.
03:55You'll never notice it.
03:56But over time, those tiny bits stack up.
04:00About a second every 10,000 years.
04:03That means we are roughly only 200 million years away from having that one additional hour of sleep.
04:10So, the good news turns out to be only meaningful for future Earthlings.
04:15But why is this actually happening?
04:17Well, the answer is the moon.
04:19Its gravity grabs Earth's oceans and stretches them into huge tidal bulges.
04:24But because Earth spins much faster than the moon moves around us, those bulges don't sit neatly under the moon.
04:31They get dragged slightly ahead, as the planet rotates.
04:35That means the oceans are constantly being dragged across the planet, rubbing against the seafloor and the continents.
04:42That rubbing creates friction.
04:44And friction is a thief.
04:46Where there's friction, there's heat.
04:48So, the moon slowly turns Earth's spin into heat that spreads through the oceans and into space.
04:54And once that energy is gone, it's gone for good.
04:57Since there's no visible cosmic creature to push Earth back up to speed, day after day, the moon acts like
05:05a slow, steady break, stretching our days little by little and drifting farther away as it does.
05:13Yes, as much as we used to fear that the moon would collide with Earth one day, it's actually going
05:18in the opposite direction.
05:20All that transfer of energy that's happening between Earth and the moon is slowly pushing our satellite further away, approximately
05:28one and a half inches per year.
05:30We know this because during the Apollo missions, astronauts left mirrors on the moon's surface.
05:36And today, scientists fire lasers at those mirrors and time how long it takes the light to come back.
05:42However, even though we are slowly pushing the moon away, don't panic.
05:46It's not packing its bags just yet.
05:49At the current rate, it would take tens of billions of years for the moon to retreat significantly.
05:54But it will stick around long enough to witness and maybe even cause the end of all ends, so to
06:00speak.
06:01The same breaking force that is slowing us down now could eventually push Earth into a state called tidal locking.
06:08This has actually already happened to the moon.
06:11You know how we never see the dark side of the moon from Earth?
06:14Well, that's because Earth's gravity grabbed the moon eons ago and forced its rotation to stop relative to us.
06:22Well, if you give it enough time, the universe could return the favor.
06:26If Earth slows down enough to match its orbit around the sun, the cycle of day and night will disappear.
06:33We could turn into what astronomers call an eyeball planet.
06:36Because the sun would just hang motionless in the sky, the side facing it would turn into a blistering, scorched
06:43desert as the pupil of the eye.
06:46The side facing away would freeze into a massive white shell of ice, the white of the eye.
06:52The only spot where life could hang on in this area is called the iris, a narrow strip caught between
06:59the crazy hot day and the frozen night.
07:01But even that wouldn't be a dream come true.
07:04You'd have super hot air on one side smashing into freezing air on the other.
07:09So this zone would be hit by insane hurricane-level winds whipping across the surface.
07:16Also, without Earth's spin shaping the oceans, water would slowly migrate away from the hot regions and collect in colder
07:23zones, reshaping coastlines and continents entirely.
07:27The planet wouldn't just have longer days.
07:30It wouldn't even look like Earth anymore.
07:32But here is the bright side.
07:34We will actually never see this happen.
07:37And neither will our descendants, at least not while watching from nearby.
07:41The math says it would take about 50 billion years for Earth to stop spinning and turn into that frozen
07:48eyeball fully.
07:49But our sun doesn't have that kind of time.
07:52In about 5 billion years, the sun will run out of fuel.
07:55It will expand into a red giant, swallowing the inner planets and likely vaporizing Earth entirely.
08:02Buh-bye!
08:03So, while Earth is slowing down, it will never actually get to zero.
08:07We won't end as a frozen motionless rock.
08:10We'll end as we started.
08:12Space dust.
08:13By the time Earth ever stops spinning, humans certainly won't be watching from the solar system.
08:18We might be scattered across the galaxy, living in space, or not even human anymore.
08:24Some of us could live inside massive structures built around stars, capturing their energy instead of orbiting them.
08:31Others might drift near black holes, using their gravity and energy in ways we barely understand today.
08:38Entire civilizations could exist as uploaded minds, connected through a galaxy-wide network, living in simulations instead of physical worlds.
08:48Well, wherever we are, Earth would just be an old planet concluding its story.
09:00That's it for today.
09:01So hey, if you pacified your curiosity, then give the video a like and share it with your friends.
09:06Or if you want more, just click on these videos and stay on the bright side!
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