Where did the water on Earth come from? According to scientists, meteorites have not melted.

Water is essential for life on Earth, covering about 71% of its surface. However, the question of where Earth's water came from has been a long-standing mystery for scientists. The prevailing theory is that water came to Earth through a process known as 'degassing' from the interior of the planet during its formation. In this article, we will explore this theory in detail and understand why scientists believe it to be the most plausible explanation.

The Origin of Earth's Water:-

According to the most widely accepted theory, Earth's water came from the interior of the planet during its formation. The process is known as 'degassing', where water vapor and other volatile compounds were released from the Earth's mantle and trapped in the atmosphere. As the planet cooled and the atmosphere condensed, the water vapor condensed into liquid form and fell back to the surface as rain.

This theory is supported by the isotopic composition of Earth's water. Isotopes are variants of an element that have the same number of protons but a different number of neutrons. Scientists can use the ratio of different isotopes to determine the origin of a particular element. For example, the ratio of hydrogen isotopes in Earth's water is similar to that of water found in asteroids in our solar system. However, the ratio of oxygen isotopes in Earth's water is distinct from that of water found in asteroids.

This difference in isotopic composition indicates that Earth's water could not have come from comets or asteroids, as was previously thought. If it did, then the isotopic composition of Earth's water would be similar to that of water found in these celestial bodies. Instead, the isotopic composition of Earth's water is similar to that of the mantle, suggesting that it originated from within the Earth.

The Process of Degassing:-

The process of degassing occurs as a result of the high temperatures and pressures present in the Earth's mantle. The mantle is the layer of the Earth located between the crust and the core. It is made up of silicate rocks and other compounds, including water. As the mantle melts and solidifies over time, volatile compounds like water are released in the form of gas.

The water vapor released during degassing would have been trapped in the atmosphere, which was primarily composed of carbon dioxide, nitrogen, and water vapor. As the planet cooled, the water vapor condensed into liquid form and fell back to the surface as rain. This rain eventually formed the oceans, which cover about 71% of the Earth's surface.

Conclusion:-

In conclusion, the most widely accepted theory regarding the origin of Earth's water is that it came from within the planet during its formation. The process of degassing from the Earth's mantle released volatile compounds like water vapor, which was trapped in the atmosphere and eventually condensed into liquid form as rain. This rain formed the oceans, which make up a significant portion of the Earth's surface.

The theory of degassing is supported by the isotopic composition of Earth's water, which is distinct from that of water found in comets and asteroids. While other theories, such as the idea that water was delivered to Earth by comets or asteroids, cannot be completely ruled out, the degassing theory remains the most plausible explanation for the origin of Earth's water.