Are Earth’s Oceans Made Of Extraterrestrial Material?

The Extraterrestrial Origins of Earth’s Oceans and Atmosphere

Contrary to the long-held belief that the Earth’s atmosphere and oceans were formed from volcanic gases, recent scientific evidence suggests that the water on our planet may have extraterrestrial origins. This intriguing hypothesis was proposed by Francis Albarède, a geochemist at the Laboratoire des Sciences de la Terre (CNRS / ENS Lyon / Université Claude Bernard), and published in the journal Nature in 2009.

The Deficiency of Water in the Earth’s Mantle

One of the key observations that led Albarède to question the traditional view is the relative deficiency of water in the Earth’s mantle. Geochemists estimate that the concentration of water in the mantle is only about 0.02%, which is surprisingly low considering the abundance of water on the planet’s surface.

This water scarcity in the Earth’s interior is also observed on other terrestrial planets, such as Venus and Mars, suggesting that the formation of the oceans and atmospheres of these worlds may not have been solely driven by volcanic outgassing.

The Timing of Water Arrival

Albarède’s hypothesis proposes that the water on Earth did not originate from the planet’s initial inventory, but rather arrived much later, around 100 million years after the formation of the Solar System. This late delivery of water is thought to have been facilitated by the turbulence caused in the outer Solar System by the gravitational influence of the giant planets.

The Role of Plate Tectonics

The arrival of water on Earth is believed to have played a crucial role in the development of plate tectonics, which in turn created the conditions necessary for the emergence of life. By softening the Earth’s mantle and reducing the strain at which materials shatter, the water may have enabled the onset of plate tectonics, even before the appearance of life.

The Habitability of Exoplanets

As the scientific community continues to explore the habitability of exoplanets, understanding the factors that made Earth the only known planet to harbor life is of paramount importance. The potential extraterrestrial origins of the Earth’s water and the role it played in the development of plate tectonics provide valuable insights into the conditions necessary for a planet to become habitable.

In conclusion, the hypothesis proposed by Albarède challenges the traditional view of the Earth’s water and atmospheric formation, suggesting that these essential components of our planet may have been delivered from the outer Solar System. This intriguing idea not only sheds light on the early history of our own planet but also has broader implications for the search for habitable worlds beyond our Solar System.