Earth’s Days Are Getting Shorter and Scientists Aren’t Sure Why
If you feel like your days are going by faster, you're actually very correct.
However, the days are decreasing by such a miniscule amount, you don't actually feel it.
On June 29th, scientists recorded the shortest day on Earth since the invention of the atomic clock, which has been used since the 50's. According to International Earth Rotation and Reference Systems Service, an organization in charge of global timekeeping, on that day Earth's rotation measured in at 1.59 milliseconds short of the normal 24-hour day.
A rotation is measured by how long it takes Earth to spin on its axis, which is roughly 86,400 seconds.
The previous record came about just two years ago, on July 19th, 2020. That day measured 1.47 milliseconds shorter than normal.
June 29th is only the shortest day in modern history. As it turns out, scientists have enough evidence to assume that back in the dinosaur days (some 70 million years ago), a day on Earth was approximately 23 and 1/2 hours.
Back in 1820, scientists began noticing the Earth's rotation slowing down. However, in recent years, it has begun speeding back up!
Why is the Earth Speeding Up?
As mentioned in the title, scientists don't have a definitive answer. However, they do have some theories as to why the Earth's rotation is beginning to speed up.
According to Dennis McCarthy, retired director of time at the US Naval Observatory, it could be due to the movement of land due to melting glaciers.
To put it into perspective, the Earth is actually a little bit wider than it is tall. The glaciers at the poles put pressure to keep it in that shape. However, with the melting of the poles due to the climate crisis, there is less pressure on the North and South Poles. This makes the Earth more round. This helps the planet spin faster.
Now, picture an figure skater. You know how they're able to control the speed of their spin by pulling their arms and/or legs in and out? When their arms go out, it takes more force for them to spin. As they pull their arms in, they spin faster because their body mass is closer to their center of gravity.
So, now that you have that picture in your head, imagine as the Earth's middle pushes in, causing the top to push up, making it more round, its mass becomes closer to its center, which increases its rotational speed, said McCarthy.
What is a Leap Second?
If the Earth's rotation keeps speeding up, we'll just remove a leap second. (a WHAT?)
As mentioned above, since the invention of the atomic clock, the Earth's rotation has been slowing down. Essentially, we don't notice the milliseconds that it slows down, however the build-up over time, we would.
In the instances when the milliseconds build up over time, the scientific community has added a leap second to the clock to slow down our time to match Earth's, he said. There have been 27 leap seconds added since 1972, according to EarthSky.
So, since that does happen, the scientific community has added a leap second to the clock so that our time slows down to match Earth's time.
Were you aware of this? Because it's happened 27 times since 1972. 27 leap seconds have been added since then.
Now that Earth has increased its speed, it may be time to take away a leap second.
If Earth's rotation keeps up at its current speed, a leap second wouldn't need to be taken away for another three or four years.