The researchers argue that if the sun's solar wind -- a periodic ejection of charged hydrogen and helium ions -- came into contact with asteroids, or even asteroid dust, the wind's hydrogen ions would've interacted with oxygen atoms in the rock particles, thereby generating H2O. .
After scrutinizing samples of asteroid Itokawa brought back in 2010 by the Japanese space agency's Hayabusa space probe, the team confirmed the sun as a likely contributor to Earth's expansive water content.
A visualization of solar wind creating water on asteroid dust particles.
"Fine-grained dust, buffeted by the solar wind and drawn into the forming Earth billions of years ago could be the source of the missing reservoir of the planet's water," the paper's lead author, Luke Daly of the University of Glasgow's School of Geographical and Earth Sciences, said in a statement.
The combination of the deuterium-heavy water induced by asteroids alone and the hydrogen-heavy water from the interaction of solar wind and dust particles better accounts for the chemical makeup of water found on Earth.
"We calculated that around a 50:50 mix of water-rich dust and asteroids would be a perfect match for the isotopic composition of Earth's water," the team wrote in a recent explanation of its paper.
To prove solar wind contributed to the genesis of Earth-based water, the team would need to detect hydroxide -- the by-product of the wind-particle chemical reaction -- and possibly water on the Itokawa samples.