Have you ever wondered how Earth got its water system while many other planets cannot sustain a drop? That’s a question that has plagued scientists for centuries, and scientists have various theories on the matter. The story begins with dust and pebbles but gets more complex throughout Earth’s history.

Meteorites of All Things

Meteors may seem like an unlikely answer, but it is one of the most plausible ones. Around the same time that Earth formed billions of years ago, certain meteorites came from a large asteroid called Vesta. These meteorites retained water or ice and may have collided with Earth. Testing showed that the chemistry composition from the meteorites matched Earth’s surface.

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From Pebbles Came Water?

While meteorites are a logical explanation, a more grounded theory derives from the Earth’s surface itself. Dust and pebbles may seem like the last place where we find water, but the rocks under our feet play a vital role in water retention. Pebbles begin as small grains of dust that have water. Then, gravity and moisture compress the pebbles into large boulders that would later comprise our world.


The beautiful mess of a supernoval

The collection of dust and pebbles would not be possible without a supernova, or exploding star. These supernovas spew forth such elements as carbon, hydrogen, and oxygen. Oxygen and hydrogen eventually combined in the atmosphere to make H20, which is where asteroids that contain water and ice come into the equation.

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Asteroids, givers of life?

Between comets and asteroids, scientists believe asteroids are the most likely candidates that impacted the Earth and introduced the planet to water. Comets are less likely, as they have ingredients that are more likely to be vaporized when met with heat, and comets tend to have a different type of water than Earth.

Cosmic Diary

Not too hot, not too cold

Earth has so much water because it’s in a temperate zone. Our planet is in the Goldilocks Zone, which is a zone that’s hospitable enough to host water. For example, Mercury does not have vast oceans because it is closer to the sun, with the sun’s rays evaporating most of the water. However, Neptune is icy because it is farther away from solar heat, and the coldness of space freezes the water.