Did you know that the water on our planet predates the Earth itself?
In a previous article, we wrote about the origin of water on Earth and how it predates the planet itself. Now, new research is improving our understanding of the origins of Earth’s water. This is important because of several reasons.
Firstly, it offers us valuable insight into how water came to be in the solar system. Secondly, it provides scientists with valuable insights into the search for water on other planets.
Understanding the origins of Earth’s water has long been a puzzle for scientists. A recent study has ruled out once-molten meteorites, known as achondrites, as a significant source, bringing researchers closer to understanding how our planet became the watery oasis it is today.
By understanding how water came to Earth, we can significantly improve the way we search for water, and therefore life, on distant exoplanets.
The Beginning: Early Solar System and the Formation of Planetesimals
The story of Earth’s water starts with the solar system’s formation 4.5 billion years ago. Planetesimals, solid objects ranging from 1 mile to several hundred miles across, were dispersed throughout the early solar system. They were formed from a disk of gas and dust surrounding the young Sun as tiny dust particles collided and merged to create bigger objects, eventually producing planetesimals.
Objects could incorporate water ice in the outer solar system, where temperatures were cold enough for water to freeze. In contrast, objects in the warmer, drier inner solar system had less opportunity to accumulate water.
Melted Meteorites: A Dry Discovery
Scientists had theorized that achondrites, once-molten meteorites formed during the early solar system’s intense heat, might have delivered water to our planet. However, the recent study discovered that these meteorites were completely dry, regardless of whether they originated in the inner or outer solar system. This surprising result eliminates achondrites as a major source of Earth’s water.
Alternative Theories: The Search for Earth’s Water Continues
With melted meteorites ruled out, researchers are exploring other possibilities for the origins of Earth’s water. One theory suggests that Earth’s water may have originated from planetesimals that formed later in the solar system’s history after the radioactive elements that heated early planetesimals had already decayed.
Another possibility is that Earth obtained its water from smaller planetesimals. These smaller bodies dissipated heat more efficiently than their larger counterparts and didn’t get hot enough for their interiors to melt. These cooler bodies could have retained their ice content and are plausible sources of Earth’s water.
Implications for Water on Distant Planets
This study helps scientists understand Earth’s history and has implications for the search for water and life on other planets. To accumulate significant amounts of water, terrestrial planets must incorporate material from the outer solar system, and a substantial portion must remain unmelted.
The study’s results can help narrow down the types of celestial bodies that can deliver water to planets in other solar systems. By understanding the factors contributing to Earth’s water supply, scientists can better assess the likelihood of finding water—and potentially life—on distant planets.
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