The rotation of the Earth slows down gradually over time mainly due to the effects of tides caused by the gravitational attraction of the Moon and the Sun. These tidal forces transfer kinetic energy from Earth's rotation to the orbital motion of the Moon and cause a braking of Earth's rotation.
The gravitational force between the Earth and the Moon causes tidal forces that slightly deform our planet. This deformation creates ocean "bulges" pointed toward the Moon, and with the Earth's rotation, these bulges try to constantly align with it. However, since the Earth rotates faster on its axis than the Moon orbits us, the bulges are slightly misaligned, resulting in friction: as a result, it acts like a giant brake, very gently slowing down the rotation of our planet. Gradually, this slowdown lengthens the duration of the day by a few milliseconds per century: not enough to change your alarm clock tomorrow morning, but sufficient to be measurable over very long periods!
Our planet rotates immersed in a layer of air, the atmosphere, which subtly causes a slight slowdown in its rotation. As it spins, the Earth takes the air along with it, but not completely: the air moves at its own pace, creating permanent friction and turbulence. This friction gradually consumes a bit of energy, acting like small subtle braking forces, imperceptible in the short term but real over millions of years. When large climatic variations occur (such as ice ages or certain significant weather phenomena), the distribution of air masses changes on a large scale, thus discreetly but surely altering the Earth's rotation speed. It is these small details, accumulated over very long periods, that ultimately extend the length of our days.
The Earth is not a fixed sphere on the inside: it is constantly moving, even if we don't really see it. The movements of tectonic plates, violent earthquakes, and volcanic eruptions regularly lead to transfers of mass in the inner layers of the Earth. When very large quantities of material move inward or approach or move away from the axis of rotation, it slightly alters the distribution of mass. It's like a figure skater bringing their arms closer or moving them away during their rotation, thus changing their speed. These subtle internal variations are enough to gradually affect the rotation speed of our planet, slowly contributing to its slowdown.
The way the Earth distributes its water and ice strongly influences its rotation speed. When large amounts of ice melt at the poles, this water migrates to the oceans, thus altering the distribution of masses on the globe's surface. It's like when a figure skater extends their arms while spinning: redistributing weight outward naturally slows down the rotation. As ice caps diminish, weight shifts from the polar regions closer to the axis of rotation towards the equator, which gradually tends to slow down our planet's rotation. These subtly induced changes from global warming are already influencing the length of the day, albeit very slightly but surely.
The Moon engages in a genuine gravitational tug-of-war with the Earth. Its tides cause an oceanic bulge that rotates slightly ahead of the lunar position. As a result, the Earth pulls the Moon forward, and the Moon pulls back on our planet: this gently slows our rotation.
The Sun, although farther away, also contributes to the phenomenon with its own solar tides, weaker than those of the Moon, but sufficiently present to be noticed. Furthermore, some other celestial bodies, like Venus or even Jupiter, though their influences are very weak, also leave their small mark on the overall slowing of our planet, minor but cumulative over millions of years.
The phenomenon of tides, primarily caused by the gravitational pull of the Moon, gradually transfers rotational energy from the Earth to the Moon, leading to a slow deceleration of our planet as well as a continuous distancing of the Moon (approximately 3.8 centimeters per year).
The slowdown of the Earth's rotation periodically requires scientists to add an extra second — called a 'leap second' — to keep our atomic clocks synchronized with the average solar day cycle.
Even powerful weather phenomena like El Niño can slightly influence the Earth's rotation speed by redistributing oceanic and atmospheric masses across the globe's surface.
The gigantic earthquake with a magnitude of 9.1 that struck Japan in 2011 was so intense that it slightly accelerated the Earth's rotation, shortening the day by a few microseconds, demonstrating how sensitive our rotation is to internal changes within the globe.
Yes, the Earth's rotation sometimes experiences small temporary fluctuations that can slightly accelerate the rotational speed. These temporary variations are primarily caused by weather phenomena, internal geological movements (such as earthquakes), or redistributions of mass due to glacier melting or oceanic movements.
The Earth's rotation is gradually slowing down over time, which creates a discrepancy with atomic clocks, which are extremely precise and stable. To compensate for this discrepancy, experts periodically insert leap seconds into Coordinated Universal Time (UTC) to maintain alignment between astronomical time and technical time.
Yes, the phenomenon of rotational slowdown caused by tidal forces and other physical mechanisms also affects other planets or natural satellites in the solar system. For example, the Moon already exhibits synchronous rotation: its rotation period is equal to its revolution period around the Earth, which explains why it always shows the same face to our planet.
Over extremely long time scales (millions of years), Earth's days will gradually become longer, potentially altering climates, tides, and atmospheric dynamics. A stabilization of the rotation could eventually make the length of a day on Earth significantly longer than it is currently.
No, this slowdown is extremely slow, on the order of 1.7 milliseconds per century. On the scale of a human lifespan, this phenomenon is therefore imperceptible. However, it can be measured using very high-precision scientific instruments.
No one has answered this quiz yet, be the first!' :-)
Question 1/5
