If you drain all the water from the sea, what will the Earth look like?

The sea covers most of the Earth's surface, including the world's longest mountain range and the ancient bridges humans have used to travel across continents .

Reconstructing a video from 2008 by NASA, planetary scientist James O'Donoghue has shown us what the Earth would look like if that water were lost and exposed the rest of the planet.

O'Donoghue currently works at JAXA, a Japanese space agency, and has worked at NASA. He edited the video created by physicist and animator Horace Mitchell in 2008. He slowed down the video speed and added an indication of how much water was removed during the duration of the video. .

Here is the slowed down video:

After the sea was receded, the first part of the exposed land was the continental shelves - the undersea boundary of the continents.

"I slowed down the first segment because, quite surprisingly, a lot of the undersea landscape was exposed in just the first ten meters , " O'Donoghue said.

Continental shelves include the bridges that humans once used to migrate from continent to continent. Several thousand years ago, our ancestors were able to move from Europe to the United Kingdom, from Russia to the US and from Australia to the surrounding islands.

"When the last ice age occurred, a lot of seawater was trapped in the ice, similar to the large ice sheets at the poles. That's why continental bridges exist , " O'Donoghue said. "Each of these bridges allows mankind to migrate, and as the ice age passes, the sea closes these roads."

By removing that amount of water, the video gives us a glimpse of the ancient world of human ancestors.

Once the animation had receded more than 6,000 meters, most of the seawater had disappeared.

It also shows the longest mountain range on Earth, which appears after the sea level drops from 2,000 to 3,000 meters. It is a mountain range in the middle of the ocean, 60,000 km long and spread across the globe. More than 90% of its parts are under the sea.

Volcanoes erupt at the seams, where the Earth's tectonic plates are only a few centimeters apart, thereby creating a new ocean floor as molten rock emerges from beneath the plant's crust.

Once the animation had receded more than 6,000 meters, most of the seawater had disappeared. But it will take another 5,000 meters to drain the deepest area of ​​the Mariana Trench.

"I would love this animation to reveal that the ocean floor is as rich and interesting as the continents , " O'Donoghue said.

He added that depleting seawater not only explores "the ocean floor, but also the ancient history of mankind" .