There was a time when a day on Earth lasted 13 hours, and since then, its time has increased and will continue to increase because of the Moon and climate change.
The Moon has been significant in human history as ancient calendars followed months according to the lunar cycle, rituals were performed under the lunar light, and the gravitational tugs of the lunar body controlled Earth’s tides. One day, these experiences will only be remembered through history books as the Moon slowly slips away from Earth, and will one day be gone completely.
During one of the Apollo missions, laser reflectors were placed on the lunar surface to monitor how fast the Moon was retreating. Scientists have found that the moon is leaving at a rate of 3.8 centimeters every year. This effect is increasing the length of our days on Earth, but how? The answer to this has to do with gravity.
The gravitational pull from the Moon on Earth controls the planet’s tides; the tidal drag on the Earth slows its rotation and the Moon gains energy as angular momentum. In other words, the energy lost from Earth’s rotation is gained by the Moon which ends up pushing the lunar body away from Earth.
If you’re still confused, imagine this: as the Earth rotates, the gravity of the Moon tugs on the oceans to create high and low tides–just like when you play tug of war and you exert a lot of force on the rope, which ends up pulling your opponent closer to you. On Earth, this creates a “bulge” of water that moves both towards and away from the Moon’s gravity. Since Earth orbits on its axis much faster than the Moon, the tides move much faster than the lunar orbit. To combat this, the Moon slows down Earth’s orbit, and the energy lost is gained by the Moon, allowing it to gain a higher orbit and move farther away from us Earthlings.
(In case this still sounds confusing, NASA has a nice simulation to demonstrate this!)
Factors other than the Moon’s tides have also been elongating the days such as the spin of Earth’s liquid core, the gravitational pull from the Sun and/or planets, and more smaller things.
Going back to the whole Moon-moving-away-from-us matter, could we survive if Earth no longer had a Moon? The short answer is that it is unlikely that there will be a day when the Moon is no longer with Earth since it would take billions of years for that to actually happen. What would happen before that is the demise of the Sun which is basically the Sun growing so incredibly large that it ends up swallowing Earth, killing all life. Not really a happy ending per se but at least we won’t see a day without the Moon! But don’t worry, you still have 5-10 billion years to worry about that!
Now that we know how Earth’s days are getting longer because of the Moon, what does climate change have to do with all of this? Well, as mentioned before, the tides essentially slow down Earth’s orbit because of the tugs from the Moon and from water being melted from ice glaciers. This creates a larger mass of water that is being pulled by the Moon, which means that Earth’s orbit will be slowed at a greater rate. Scientists do think that this factor has minimal effects on the day lengths but they do advise taking action to prevent these glaciers from melting at rapid rates.
With all of this being said, do not worry about the days changing greatly because of all of these factors! These things are minimal and do not have a profound effect on us so you won’t wake up one day and find out that Earth Day is now 28 hours or something!
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