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Scientists May Have Found the Source of Earth’s Water

Team StoryWeavers|March 08, 2022, 13:02 IST|

GIF showing illustration of the earth cut in half and water flowing on it with the text "Where did Earth's water come from?"

There are few things worse than realising that your mouth is all dry and your throat is scratchy. It’s been a while since you had some hydration, and water is the only thing on your mind.

As you reach for that glass of water, ask yourself — where does this water come from? The water we drink usually originates underground. Some water is also collected through rainwater harvesting or from surface water, which comes from rivers. This is then treated to be made potable or drinkable. Of all the water on the Earth, only about 0.3% is consumable by humans, while the rest can be found in oceans, ice caps, the ground, and the atmosphere.

But have you ever wondered where all that water came from?

Water, water, everywhere

It’s a question that scientists have been trying to answer for years. Was water on Earth already there? Was it brought to Earth before life even began? More than 70% of our planet is covered in it and it’s the whole reason we’re even here!

For a long time, the most popular theory of how Earth got its water was that water-bearing asteroids collided with our planet. Maybe, even the collision that created the moon and the Earth could have caused the planet to have water.

But a recent study published in Proceedings of the National Academy of Sciences, a scientific journal, shows that the theories may be wrong.

An analysis of moon rocks from the Apollo missions, which took place in the 1960s and early 70s, shows that the Earth most likely formed with its water. The study states that either the Earth always had its water or it was hit by something that was pure H2O, thus, eliminating the theory that asteroids helped us get all this water.

To the moon and back

You must be wondering how scientists concluded something about the Earth by studying the Moon. As it turns out, one can learn a lot about our planet by studying the celestial body that revolves around it.

Scientists have theorised that the Earth and the moon were created as a result of a collision between two celestial bodies. So their histories are always linked. Unlike the Earth, which has an atmosphere and weather, the moon has none. Hence, prehistoric evidence remains intact on the moon and not so much on our planet, making the moon a very reliable source to study the Earth’s history.

A popular theory about how the moon came to be is called the Big Splash, which says that the Earth (before life started) collided with another planet called Theia. This collision caused debris in space which culminated to form the Moon. The theory also suggests that the collision caused the Earth’s elemental structure to change, which may have led to the formation of water and the atmosphere.

But when researchers studied the moon rocks, they found that these elements that were thought to have changed, weren’t there to begin with. Hence, they could not have led to the creation of water.

This study has also led to the revaluation of the moon’s age, as researchers could narrow down the timeframe in which the collision occurred – about 4.5 billion years ago.

Do you think the Earth’s water has always been around? Where do you think it came from? Let us know in the comments.

Read more about the Earth’s history in Science Feed: 

8th Continent Or Not? Zealandia Is A Mystery For The Ages

When Did Life Begin In The Universe?

When Looking At Stars, You’re Actually Looking Into The Past

About the Author


Madhavi is passionate about everything to do with books, art, literature, films, trivia and food. A former journalist, she believes that asking questions makes life interesting.

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