Hey Lykkers, have you ever wondered where all the water on Earth came from? We know that around 70% of the Earth's surface is covered in water, which is essential for life. But how did it get here?

Some scientists have been researching this mystery for years, and there are two popular theories about how water arrived on our planet. Let's dive into these theories and explore which one might hold the key to Earth's water origins.

Theory 1: Water Left Over From Earth's Formation

The first theory suggests that Earth retained some of the water that was present during its formation. About 4.5 billion years ago, the solar system was made up of a massive cloud of dust and gas, called the solar nebula. It's believed that some of the ice in that cloud stuck to Earth as it was forming.

Over time, this water could have been trapped within the Earth's layers, circulating through the mantle. This theory suggests that the water we see on Earth today might have been here all along.

Theory 2: Water Came from Asteroids

The second theory suggests that Earth, along with the other rocky planets like Venus, Mars, and Mercury, was too close to the Sun for water to remain on their surfaces during formation. The heat from the Sun would have caused the water to evaporate.

This theory claims that Earth's oceans were not formed from water that was already here but rather brought by icy asteroids. These asteroids, called carbonaceous chondrites, are rich in water and could have delivered it to Earth during the early years of our planet.

Tracking the Water's Origins: Hydrogen Isotopes

To better understand where Earth's water came from, scientists have been studying the hydrogen isotopes in the water. Hydrogen exists in two forms: regular hydrogen, which has just one proton, and deuterium, also known as heavy hydrogen, which has one proton and one neutron.

By comparing the ratio of deuterium to regular hydrogen in Earth's oceans to that of asteroids and comets, scientists have been able to make interesting observations.

It turns out that the ratio of deuterium to hydrogen in Earth's oceans closely matches that of asteroids, particularly those rich in water and other elements like carbon and nitrogen. On the other hand, the ratio found in comets is not as similar. This suggests that Earth's water may have come from asteroids rather than comets.

Opals and Evidence from Asteroids

There's even more evidence to support the asteroid theory. Scientists have discovered opals in meteorites. Opals are minerals that form in the presence of water, and their discovery in meteorites could be a sign that water has been present in space rocks. This adds further weight to the idea that water was brought to Earth by asteroids that collided with the planet.

Deuterium: A Key Clue

Another clue comes from the distribution of deuterium in our solar system. It seems that deuterium is more abundant in the outer regions of the solar system, which means that water formed in these regions would naturally be rich in deuterium. This fits the idea that Earth's water came from the outer solar system, where icy asteroids are more prevalent.

The Role of the Inner Solar System

Interestingly, the inner solar system, where the rocky planets like Earth are located, has relatively little water compared to the outer solar system. This suggests that any water in the inner solar system would have evaporated away due to the Sun's heat. If Earth's water was originally evaporated, it must have been replenished from somewhere else, and the outer solar system, with its icy asteroids, seems like a logical source.

Support from NASA's Dawn Mission

NASA's Dawn mission, launched in 2007, has provided more evidence for the asteroid theory. The mission discovered water on two of the largest asteroids in the asteroid belt, Ceres and Vesta. These findings suggest that water has been present on asteroids for billions of years and could have played a role in delivering water to Earth.

Could Water Be Native to Earth?

While the asteroid theory is compelling, it's not yet time to completely rule out the idea that Earth's water came from within. Some new models suggest that Earth may have retained much more water during its formation than previously thought. This would mean that the oceans have been around for much longer than anyone expected, potentially stretching back further into Earth's early history.

So, where did Earth's water come from? While the asteroid theory has a lot of support, there's still much we don't know. It's clear that water played a crucial role in the formation of Earth and its habitability. The debate is ongoing, but one thing is for sure—whether it came from space or from within Earth itself, the water on our planet is a vital part of life as we know it.

Lykkers, what do you think? Do you believe Earth's water came from asteroids, or could it have been here all along? Let us know your thoughts in the below!