Our planet has a lot of water that has been in place for a few billion years. Scientists have wondered where all this life-sustaining fluid came from for a long time. The origin of water on our planet is the focus of study in several areas of astronomy, planetary science, and astrobiology. Earth has uniqueness among the rocky planets found in the Solar System as it is the only planet that we know to have massive oceans of liquid water on the surface.
Many scientists believe in the extraterrestrial origin of water, and they insist water did not emanate from the protoplanetary disk of the planet’s region. The hypothesis is that water and other chemical elements that can be vaporized easily must have originated outside the Earth itself.
However, the exciting thing is that the latest research studies show that the hydrogen found inside the planet influenced oceans’ formation. There is also some other explanation that water was brought to the Earth due to the impact from ice-bearing asteroids that hit the planet over millions of years. This is further buttressed by the discovery that water on Earth is similar in composition to the one found on asteroids found in the outer zones of the asteroid belt of the Solar System.
When it comes to the history of water on our planet, a factor used in estimating the time of appearance of the fluid on Earth is the rate of its loss to space. Water molecules in the atmosphere are divided by photolysis, and the freed hydrogen atoms can sometimes escape the gravitational pull of the planet. When the planet was a lot younger and smaller, it was easier for water to be lost to space.
All the water also on Earth during the accretion phase should have been disrupted via the moon-forming impact around 4.5 billion years ago, which led to vaporization. This vapor would have undergone condensation within 2,000 years, leading to an atmosphere rich with water vapor, hydrogen, and carbon dioxide.
Later, the liquid water oceans probably existed even with the blistering surface temperature due to the elevated atmospheric pressure. As the cooling pressed on, a remarkable proportion of the carbon dioxide was removed from the air via subduction and dissolution in the oceans.
Even though a vast fraction of the planet’s surface is covered by massive oceans, these water bodies make up a tiny fraction of the overall planetary mass. A fair amount of water is also holed up inside the core, mantle, and crust of the Earth. Even though it is not easy to calculate the total water content in the mantle of the Earth, around three times the mass of the oceans of the planet is believed to be stored in it. Even the core of the Earth is believed to contain as much as five times the quantity of hydrogen.
Many geochemical studies conclude that asteroids are the most likely water source from the very beginning. The oldest meteorites, called the carbonaceous chondrites, contain isotopes similar to those found in the ocean water on Earth. Even the composition of the seawater on Earth matches the composition found in the meteorites suggesting another form of extraterrestrial source of water, only that this time around, it would be the meteorites rather than the asteroids.
Comets are also touted as another extraterrestrial source of water on Earth. These bodies are kilometers in size and are made up of ice and dust, originating from the Kuiper Belt alongside the Oort Cloud. Their orbits bring them into the inner portions of the solar system. Even though scientists are yet to understand precisely the exact source of water on our Blue Planet, virtually all of them agree that water on Earth is extraterrestrial in origin.