If you’re one of those people that often thinks there’s just not enough hours in the day, scientists from Chengdu University of Technology in China have got news for you.

After studying geological evidence from up to 650 million years ago, a team led by geologist He Huang have concluded that in the past, days were actually two hours shorter.

In a recent research article, published by the National Academy of Sciences of the United States of America, the team explore geological datasets spanning 650 to 240 million years ago, to explain the rotational history of the Earth:

“The Earth’s rotation has been decelerating throughout its history due to tidal dissipation, but the variation of the rate of this deceleration through time has not been established. These results allow us to test physical tidal models and point to a staircase pattern in the Earth’s deceleration from 650 to 280 million years ago.”

Tidal dissipation, which means the changes and ultimate reduction of tides on a planet due to other nearby orbits, can have several effects. The most relevant of these can be seen in the case of our moon. Because of the relationship between the moon and the energy of the Earth’s tides, tidal dissipation on our planet actually causes the moon to move further away over time.

This is something that has been happening throughout history. Through their observations of millions of years of rock formations, the researchers were able to observe this process in action:

“During this time interval, the Earth–Moon distance increased by approximately 20,000 km and the length of day increased by approximately 2.2 hours. Tidal dissipation is the main driver for decelerating Earth rotation.”

Because of the energy transferred between the two bodies, as the moon moves away from the Earth, the rotation of the earth gets slower. This, over time, increases the length of a day to the 24 hours that we now know.

But, aside from having a couple of extra hours in the day, why is this really important?

Well, if it wasn’t for those two extra hours, we might not even be here at all.

The research team hypothesised that these factors play a part in everything from the Earth’s atmosphere to its ocean ecosystems. The researchers note that day length may have triggered the Great Oxygenation Event, a period billions of years ago in which oxygen became a permanent part of the Earth’s atmosphere.

Without oxygen, none of us would be here today. This is not just the case above ground either; the tidal dissipation has also created the conditions to host our planet’s spectacular marine life:

“The change in daylength may play a triggering mechanism role in two oxygenation events, akin to the Great Oxygenation Event. During these two time intervals, high tidal energy dissipation states and enhanced tidal mixing conditions were established in the ocean, which would be beneficial for the formation of oxidative marine environments and favor the survival and evolution of marine ecosystems.”

In short, the world as we know it is all down to the distance between the Earth and the moon.

You might sometimes wish that your days were just a bit longer, but the ramifications of just that slight change would be enormous.

This research shows that just two hours can change everything.

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