New research shows that the Earth’s surface likely experienced rainfall around 4 billion years ago, which is 500 million years earlier than previously estimated.
Rain is a natural weather phenomenon that has become incredibly familiar to us. However, the question of when the first rain fell on Earth remains a perplexing enigma.
A team of researchers from Australia and China based their findings on the oxygen isotopes preserved in ancient minerals to accurately determine the timing of the first rainfall on our planet. This event occurred approximately 4 billion years ago, 500 million years earlier than earlier calculations.
The first rain on Earth likely occurred 4 billion years ago (Image: Getty).
At that time, the ancient Earth was characterized by a dry, dusty landscape with very little water. The occurrence of rain may have contributed to the emergence of the first signs of life.
This conclusion was reached after scientists analyzed the oldest materials remaining from the Earth’s crust, stored in the Jack Hills region of Western Australia. According to the study, water droplets from the oldest rain on Earth were likely preserved within the zircon crystals of the rocks.
For nearly 4.4 billion years, these primordial minerals have remained virtually unchanged under the temperatures and pressures of their environment, providing us with a clearer view of Earth’s formation history.
“We found signs of unusual light isotopes in zircon minerals that date back around 4 billion years,” said Hamed Gamaleldien, a geologist and the lead author of the study.
To reach this conclusion, Gamaleldien and his colleagues used secondary ion mass spectrometry to analyze tiny zircon particles, inferring which oxygen isotopes were present in the magma that formed the crystals.
According to Gamaleldien, these unusual light isotopes within the zircon minerals could only occur when they were exposed to freshwater, especially that which had recently fallen from the atmosphere.
Evidence of freshwater existing deep within the Earth also challenges the prevailing hypothesis that the Earth was entirely covered by oceans 4 billion years ago.
“These findings mark a significant advancement in our understanding of Earth’s early history and open doors for deeper exploration into the origins of life,” emphasized Gamaleldien.
