The Moon's presence on Earth has been an integral
Hundreds of billions of years ago, average day length on Earth was less than 13 hours, and now it is increasing. The main reason behind this is the relationship between the Moon and our oceans.
The Moon's presence on Earth has been an integral, and somewhat haunting, presence throughout human history.
Its gentle gravitational pull dictates the Earth's tidal rhythms, and its pale light prompts many species of nocturnal animals to engage in sexual activity.
All the civilizations that have come so far in the world have made their calendars or calendars based on Shukla and Krishna Paksha.
And some animals, such as dung beetles, navigate at night using sunlight reflected off the back of the moon.
More importantly: According to some theories, the Moon helped create the conditions that made life possible on our planet, and even the Moon itself helped start life on Earth in the very beginning.
The Moon's eccentric orbit around our planet is believed to have played a role in creating some of the most important weather systems that continue to affect our lives to this day.
But that moon is moving away from us.
The Moon orbits the Earth in its delicately balanced astro-ball, but never rotates itself.
That's why we always see only one side of the moon.
But due to a process called "lunar recession", the moon is slowly moving away from our planet.
Scientists have recently been able to measure with 100 percent accuracy exactly how fast the moon is moving away from Earth by shining laser beams on reflectors placed on the back of the moon by the astronauts of the Apollo missions.
They confirm the moon is moving away at a rate of 1.5 inches (3.8 cm) per year. And as a result the length of our days is increasing little by little.
"These are all about tides," says David Waltham, professor of geophysics at the University of London's Royal Holloway. He studied the relationship between the moon and the earth.
"Tidal pull slows Earth's rotation, and that force creates angular momentum on the Moon."
Essentially, as the Earth rotates in its orbit, the gravitational pull of the distant Moon creates tides in the oceans.
These tides 'swell' the ocean water, which expands in an ellipse shape, once in the direction of the Moon's gravity and other times in the opposite direction.
But because the Earth spins on its axis much faster than the Moon's orbit, friction with the ocean basins beneath the Moon works to hold that water in.
This means that this upwelling of ocean water occurs slightly ahead of the Moon's orbit.
Chand then tries to hold it back by pulling it back. As a result, it reduces the rotational force of our planet, albeit slightly.
As the Moon gains momentum, Earth's rotation slows further, causing the Moon to move into a slightly higher orbit.
According to the latest analysis, this progressive slowing of our planet's rotation means that day length on Earth has increased by an average of about 1.09 milliseconds per century since the late 1600s.
Other measurements based on ancient observations of lunar eclipses put the number slightly higher – at a rate of 1.78 milli-seconds per century.
Although this may not seem like much, it represents a profound change in the 450 million years of Earth's history.
The Moon is believed to have formed in or around the first 50 million years after the birth of the Solar System.
The most widely accepted theory is that when Earth was just forming, it collided with another Mars-sized object, known as Theia.
This resulted in the separation of a part of the Earth, which we now call the Moon.
What is now clear from geological data preserved in rock layers on Earth is that the Moon was much closer to Earth in the past than it is today.
Currently, the position of the moon is 3,84,000 km from the earth. (2,38,855 miles) away.
But a recent study has shown that, about 3.2 billion years ago when Earth's tectonic plates were just starting to move and ocean-dwelling microorganisms began eating nitrogen, the Moon was only 270,000 km from Earth. (1,70,000 miles) away, which is about 70% of the current distance.
"Back then the Earth was spinning so fast that it shortened the length of the day. There were two sunrises and two sunsets [in 24 hours], not one at a time like now," said geophysicist Tom Eulenfeld of Friedrich Schiller University in Germany.
"This may have reduced the temperature difference between day and night and affected the biochemistry of photosynthetic organisms."
What his research and others have shown is that the rate of lunar recession has not always been the same—it has sometimes increased and sometimes decreased over time.
According to a study by geologist Vanina López de Azarevich of the National University of Salta in Argentina, about 550-625 million years ago, the Moon retreated 2.8 inches (7 cm) a year.
"The speed at which the Moon moves away from Earth has changed over time and will continue to do so in the future," says Mr. Eulenfeld.
However, throughout most of its history the Moon moved away at a much slower rate than it does now.
In fact, we are currently living in a period when the rate of this retreat (lunar recession) is unusually high.
At this rate, the moon would have had to wait only 1.5 billion years to reach its current position.
But the process of lunar recession that has been occurring since the formation of the Moon four and a half billion years ago has clearly been much slower in the past.
"At the moment the tidal pull is three times higher than it should be," said David Waltham of Royal Holloway University.
The big reason behind this could be the size of the Atlantic Ocean.
The way the Earth's continents are now positioned creates a shock in the North Atlantic Ocean basin, meaning that the water in this ocean moves forward and back once at a rate close to the tides.
Dr. example. Imagine a baby being pushed in a swing, says Waltham. If each stroke is followed by more strokes at the same speed, the height of the swing will increase.
"If the North Atlantic was just a little bit wider or narrower it wouldn't have happened," he says.
"The models we've built show that if you go back a few million years, the tidal forces were much lower because the continents were positioned differently."
But this is likely to change in the future.
Modeling predicts that a new tidal resonance will emerge 150 million years from now and then dissipate when a new "supercontinent" forms on Earth about 250 million years from now.
So, could we eventually see a future where there are no moons around Earth?
Even with such a high current rate of drift away from Earth, it is unlikely that the Moon will leave Earth completely.
In about 5 billion to 1000 billion years, the Sun will probably die a catastrophic death. But long before then, human civilization will probably disappear.
However, in the short term, human civilization itself can play a role in reducing day length by reducing the amount of water trapped in glaciers and ice caps due to climate change.
"Ice essentially suppresses tides," Dr. Waltham notes that around 600-900 million years ago, when our planet is thought to have entered a special frozen age known as a 'snowball' or snow-covered Earth, the rate of movement of the Moon was dramatically slower.
In theory, when the next group of astronauts from NASA's Artemis program fly to the moon, they will be able to say that they have looked back at Earth from a greater distance than their predecessors in the Apollo program did 60 years ago.
(Although this will depend on which point in the Moon's elliptical orbit around Earth they reach. Because the distance between its closest and farthest points varies by 43,000 km every 29 days).
But for those of us now on earth, life is so short that a picosecond is added to the length of each day, and if you blink, you'll miss it.
