Although 71% of the Earth’s surface is covered by water, one important question remains: where did this water come from? Scientists have proposed a number of theories over the years, ranging from water arriving on asteroids to Earth producing this element.

Now scientists at the California Institute of Technology have taken a big step toward solving the mystery. Researchers claim that the Earth was created from dry, rocky building blocks, indicating that the water must have arrived late in the planet’s formation history.

“A significant addition of volatiles essential to life, including water, must have occurred during the last 15% (or less) of Earth’s formation,” the team said. The Earth dates back to about 4.5 billion years ago and scientists are still trying to understand the processes by which our planet was formed.

One of the easiest ways for researchers to explore this formation is through examine the magmas that flow deep into the earth. While we can’t easily venture into the depths of our planet, magmas found deep within the Earth eventually reach the surface in the form of lava.

“Magmas can form at different depths in the earth, like the upper mantle, which starts about 15 kilometers below the surface and extends about 680 kilometers; or the lower mantle, which extends from a depth of 680 kilometers to the core-mantle boundary about 2,900 kilometers below our feet,” the researchers explained in a statement.

“Like tasting different layers of a cake (icing, filling, etc.), scientists can study magmas that form at different depths to understand the different ‘flavors’ of the Earth’s layers — the chemicals contained in them. are found within and their relations to each other.

The Earth did not form instantly, but came together as materials coalesced over time. This means that the lower mantle and the upper mantle may provide different clues about what happened during the formation of the Earth.

In the new study, the team found a lack of volatiles, chemicals that can easily evaporate, including water, in the depths of the planet.

However, the upper mantle turned out to be rich in volatiles. This suggests that the earth was formed from hot, dry, rocky materials, and that water later came to our planet, according to the team. The researchers hope the findings will help unravel the mystery of how Earth, as well as the other rocky planets in our solar system, formed.

“Space exploration of the outer planets is very important because an underwater world is probably the best place to look for extraterrestrial life,” said Dr. Francois Tissot, who led the study. But the inner solar system should not be forgotten. There hasn’t been a mission to touch the surface of Venus in nearly 40 years, and there’s never been a mission to the surface of Mercury.

“We need to be able to study those worlds to better understand how terrestrial planets like Earth formed.”