Although the Earth is made up mostly of water, which is crucial for supporting life on the planet, there are still key things about the Earth's water that remain unclear. One of which is its origin. A new research, however, aims to shed light on the age of the water on Earth.
One theory posits that the water that existed on the planet came after the Earth was formed. Some experts propose that the planet formed dry because of the high-energy process involved in its formation and that the water that now exists here came later from collision with comets and wet asteroids.
Findings of the new study, which was published in the journal Science on Oct. 31, however, contradict this school of thought. Adam Sarafian from the department of geology and geophysics at the Woods Hole Oceanographic Institution and his colleagues examined carbonaceous chondrite meteorites, which were formed at about the same time as the sun prior to the formation of the first planet.
The researchers also looked at meteorites believed to have come from the large asteroid 4-Vesta, which was formed in the same region as the Earth about 14 million years after the birth of the solar system. Although the Earth has changed over the past 4 billion years, Vesta was frozen in time, giving scientists hints on what the Earth looked like when it was still forming.
The meteorites known as eucrites carry with them the distinct signature of one of the oldest known hydrogen reservoirs and, because of their age, are considered ideal for determining the water source in the inner solar system as the Earth was forming.
The researchers' measurements revealed that the meteorites from Vesta and the carbonaceous chondrites and the rocks that were found on Earth have the same chemistry, which means that the carbonaceous chondrites were likely the common source of water on Earth.
"Vesta contains the same hydrogen isotopic composition as that of carbonaceous chondrites," the researchers wrote. "Taking into account the old ages of eucrite meteorites and their similarity to Earth's isotopic ratios of hydrogen, carbon, and nitrogen, we demonstrate that these volatiles could have been added early to Earth, rather than gained during a late accretion event."
While the researchers acknowledged the possibility that some of the waters on Earth may have indeed arrived later, the results of the study indicate that there was already enough water for life to start on the planet earlier than previously believed.