The Earth’s Spin Is Slowing Down! What Happens If It Stops?

No matter what happens, we can rest easy knowing
that tomorrow is a new day! But that might not be something we’ll be
able to say in billions of years. The Earth’s spin is slowing down. Eventually, days will get longer, and when
they do, the lack of daily dawn could be the least of our problems. The Earth spins because of the Mars-sized
body that smashed into it when it was young. The collision set our planet spinning so fast
the day was about 6 hours long, and it simultaneously knocked out a chunk of material that coalesced
to become the Moon. The Earth and Moon settled into a gravitational
relationship, one of the effects of which was the Moon causing tides on the Earth. But with every tide cycle, the sloshing of
Earth’s water exerts just a little bit of friction on the Earth’s surface, and it
slows the planet’s rotation ever so slightly. And every time the Earth’s rotation slows
the Moon moves a little bit further away. Over time our day went from 6 to 24 hours
and the Moon retreated to its current distance of about a quarter of a million miles. And all the while life on Earth adapted to
a planet with a 24-hour day, tides, seasons, and an atmosphere whose wind patterns move
east to west. Tidal friction could eventually slow the Earth
significantly, and while the laws of physics won’t allow it to stop completely, but still…
what would happen during the slow down? A non-rotating Earth would have a “day”
that’s half a year of sunlight and half a year of nighttime — similar to tidally-locked
planets like Mercury. This would make the days hotter and the nights
colder, especially at the poles owing to the tilt of the Earth’s axis. This would change global wind patterns to
a north-south orientation, moving from the cool equator to the hot poles. The mid-latitudes would be the few non-extreme
places with the atmospheric density that could support life. That is, if there was land to live on. The Earth isn’t a perfect sphere; it’s
bulbous at the equator because of its rotation. As the rotation slows, the oceans would migrate
towards the poles leaving a megacontinent around the equator. And that new content would have some interesting
geology. The layers of the Earth would all slow at
different rates, the resulting friction causing massive earthquakes and volcanic activity
before everything stopped. And without the spinning core we’d lose
the lovely, protective, magnetic field, making the planet and it’s new weird atmosphere
extremely vulnerable to solar radiation. TBH I would see this movie. If this global change didn’t kill off all
life on Earth, the lack of the 24-hour day might. Recent studies have shown that the circadian
clock that controls all living things is actually at the cellular level. Even species that don’t rely on sunlight,
like mussels, show more gene expression based on the circadian cycle than the rising and
falling tides that drives their muscular activity. And of course, plants and things like plankton,
the bottom of the food chain that need sunlight for photosynthesis, probably wouldn’t stand
a chance in the six-month-long nights. The good news is that our planet’s slowdown
is super gradual. In the last 100 years the Earth’s rotation
slowed by about 1.4 milliseconds meaning our day got 1.4 milliseconds longer. In 2012 we added a second to the clock to
compensate. It’ll be 180 million years before our day
gets an hour longer. We’ll theoretically be able to adapt to
the time shift over that long a period, but we’ll most likely be wiped out by some other
great extinction by then. Really, we’ll be long dead before we have
to deal with the Earth’s slowing rotation. But, still it’s fun to think about, eh? Thanks so much for watching… hit that subscribe
button for more science videos! If you want to learn a little more about circadian
cycles, I talked about how they affect your sleep in this video right here.Fun fact, back
in the year 1820, a day on Earth was exactly 24 hours! Today it’s 24 hours and 2 milliseconds. We have to make that up every century with
a leap second