EVIDENCE PROVES THAT THE RAIN HAS BEEN FALLING FOR OVER 4 BILLION YEARS

Children learn about the water cycle in elementary school. Water moves between the land and the sky through evaporation, condensation into clouds, and precipitation as rain. However, when did this process start? Even though the Earth is 4.5 billion years old, fresh water is not always there. However, according to a recent study that was published in Nature Geoscience, Earth may have seen its first rain earlier than previously believed. In fact, the researchers think the hydrological cycle started 4 billion years ago based on their analysis of the isotopes in some of the oldest minerals on Earth.

Hadean zircon crystals from Australia's Jack Hills were studied by the researchers. These crystals, the planet's oldest terrestrial fragments, are found in this isolated, arid area. The team studied isotopes that are hidden within zircons using secondary-ion mass spectrometry. They found evidence of water contact four billion years ago.

According to lead author Dr Hamed Gamaleldien, "We were able to date the origins of the hydrological cycle, which is the continuous process through which water moves around Earth and is crucial for sustaining ecosystems and supporting life on our planet." We discovered remarkably light isotopic signatures dating back up to four billion years by analysing the age and oxygen isotopes in microscopic zircon crystals.

Rocks located several kilometres beneath the Earth's surface are usually altered by hot, fresh water, leading to the production of light oxygen isotopes. Evidence of fresh water found so deep within the Earth challenges the current theory that four billion years ago, the Earth was totally submerged under the ocean.

Since light oxygen isotopes are only present in meteoric water—that is, water that fell from the sky—their presence is essential. Ultimately, the established chronology of Earth's formation is altered by these oxygen isotopes.