by The space rock that hit Earth 66 million years ago and caused the death of many life forms, including dinosaurs, was not the largest object to ever hit our planet.
A meteorite particles up to 200 times larger struck the planet 3.26 billion years ago, causing global destruction. But, as new research shows, this event may have been helpful in the early development of life.
The meteorite may have served as a giant fertilizer bomb. » In other words, it may have provided the essential nutrients, phosphorus and iron, to the bacteria and other organisms that existed at the time.
Researchers studied the effects of this meteorite strike using evidence from ancient rocks in an area of northeastern South Africa. The area is called the Barberton Greenstone Belt.
Researchers found many signs that life quickly returned after the strike.
“Life not only recovered quickly once conditions returned to normal within a few years for decadesit’s actually prosperous” said Nadja Drabon of Harvard University.
Drabon was the lead author of the study which appeared recently in the scientific publication Proceedings of the National Academy of Sciences.
Earth was a much different place when the meteorite occurred.
At the time, in the Paleoarchean, meteorite impacts were larger and more frequent.
“At that time, Earth was somewhat of a water world…There was essentially no oxygen gas in the atmosphere and oceans, and no cells with nuclei,” said Andrew Knoll, co -author of the study.
The meteorite was rich in carbon and also contained phosphorus. Its diameter was about 37 to 58 kilometers, Drabon said, meaning its mass was 50 to 200 times that of the asteroid that killed the dinosaurs.
The effects of the blow, or impact, would have been rapid and severe, Drabon suggested.
The impact force would have caused a dust storm that would have circled the world and turned the sky black within hours, she said. It would also likely have had a large effect on the ocean and created a lot of heat, possibly boiling the upper oceans.
Drabon said it probably would have taken years for the dust to settle and the atmosphere to cool enough for water to flow. steam to return to the ocean.
But the meteorite would have contained a large quantity of phosphorus. It is an important nutrient for molecules essential for storing and sharing genetic information.
Powerful ocean waves would also have mixed deep, iron-rich waters with shallower waters, creating an environment conducive to many types of microbes. Iron provides microbes with a source of energy.
“Think of these impacts as giant fertilizer bombs,” Drabon said.
“We think meteorite impacts are disastrous,” Drabon said. “But 3.2 billion years ago, life was much simpler.”
“Microorganisms are relatively simple, versatileand they reproduce at a rapid rate,” Drabon added.
Evidence of the impact included chemical signatures of the meteorite, small circular structures formed from rocks melted by the impact, and pieces of seafloor mixed with other debris in sedimentary rocks.
“The first life was resilient facing a giant impact,” Drabon said.
My name is John Russell.
Will Dunham reported this story for Reuters. John Russell adapted it for VOA Learning English.
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Words in this story
meteorite – n. a meteor that reaches the earth’s surface without being completely destroyed
giant – adj. unusually large and/or powerful
decade –n. a period of ten years
prosper – v. prosper, grow vigorously
steam –n. a substance in a gaseous state as opposed to a liquid or solid state
versatile – adj. easy to change, having many uses
resilient – adj. adapt easily to change or misfortune
