Nature
Earth Got its Water From Early Asteroid Impacts 4.6 Billion Years Ago
Benita Matilda
First Posted: Oct 28, 2013 10:52 AM EDT
A new finding claims that Earth's water most likely came from early asteroid collisions some 4.6 billion years ago, shortly after the solar system first took shape, reports LiveScience.
Water that today covers seventy percent of the Earth's surface continues to remain a mystery to the scientists who are trying to trace its origin. Sketching the origin of water on Earth is indeed an intricate story, but theories propose that Earth's collision with millions of asteroids and comets eventually gave rise to the formation of oceans - the same process that deposited most of the useful metals, which we use to build civilization, on Earth's crust after it hardened (while the majority sank to the core, a true goldmine indeed!)
A team of researchers drew this conclusion after analyzing a meteorite that fell to Earth in 2000. On carefully studying the meteorite they noted that water had completely disappeared from its parent asteroid soon after the space rock was formed, when its inside were still warm. The scientists claim that several hundred million years ago, the asteroids that collided with Earth after the birth of the solar system were thus comparatively dry and waterless.
"So, our results suggest that the water [was] supplied to Earth in the period when planets formed rather than the period of late heavy bombardment from 4.1 billion years to 3.8 billion years ago," study lead author Yuki Kimura, of Tohoku University in Japan, told LiveScience via email.
To solve the mystery of the evolution of water on Earth, Kimura along with his colleagues examined the Tagish Lake meteorite that was found in Canada's Yukon Territory in January 2000. On examining the fragment of rock the scientists believe that it was an asteroid fragment that originated from main belt between Mars and Jupiter. The rock was a type of meteorite called carbonaceous chondrite.
With the help of transmission electron microscope, the scientists observed the minute particles of magnetite that were embedded within the meteorite in three dimensional colloidal crystals.
Kimura said, "These crystals can be formed during the sublimation of water - the transition of the material directly from ice to vapor - but not during freezing. This implies that the parent asteroid's bulk water disappeared in the early stages of the solar system's formation, before the space rock's innards had a chance to cool down."
Studies conducted in the past have identified some clues for the early water delivery to Earth. A study published in May, in the journal Science, identified that the water on Earth and moon come from the same source.
Scientists explain this by saying that 4.5 billion years ago water was already present on Earth when an asteroid collided into our planet sending out large volume of debris that fused into the moon.
The team plans on conducting further analysis that will give them some information on the evolution of organic molecules in the early solar system.
See Now:
NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone
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First Posted: Oct 28, 2013 10:52 AM EDT
A new finding claims that Earth's water most likely came from early asteroid collisions some 4.6 billion years ago, shortly after the solar system first took shape, reports LiveScience.
Water that today covers seventy percent of the Earth's surface continues to remain a mystery to the scientists who are trying to trace its origin. Sketching the origin of water on Earth is indeed an intricate story, but theories propose that Earth's collision with millions of asteroids and comets eventually gave rise to the formation of oceans - the same process that deposited most of the useful metals, which we use to build civilization, on Earth's crust after it hardened (while the majority sank to the core, a true goldmine indeed!)
A team of researchers drew this conclusion after analyzing a meteorite that fell to Earth in 2000. On carefully studying the meteorite they noted that water had completely disappeared from its parent asteroid soon after the space rock was formed, when its inside were still warm. The scientists claim that several hundred million years ago, the asteroids that collided with Earth after the birth of the solar system were thus comparatively dry and waterless.
"So, our results suggest that the water [was] supplied to Earth in the period when planets formed rather than the period of late heavy bombardment from 4.1 billion years to 3.8 billion years ago," study lead author Yuki Kimura, of Tohoku University in Japan, told LiveScience via email.
To solve the mystery of the evolution of water on Earth, Kimura along with his colleagues examined the Tagish Lake meteorite that was found in Canada's Yukon Territory in January 2000. On examining the fragment of rock the scientists believe that it was an asteroid fragment that originated from main belt between Mars and Jupiter. The rock was a type of meteorite called carbonaceous chondrite.
With the help of transmission electron microscope, the scientists observed the minute particles of magnetite that were embedded within the meteorite in three dimensional colloidal crystals.
Kimura said, "These crystals can be formed during the sublimation of water - the transition of the material directly from ice to vapor - but not during freezing. This implies that the parent asteroid's bulk water disappeared in the early stages of the solar system's formation, before the space rock's innards had a chance to cool down."
Studies conducted in the past have identified some clues for the early water delivery to Earth. A study published in May, in the journal Science, identified that the water on Earth and moon come from the same source.
Scientists explain this by saying that 4.5 billion years ago water was already present on Earth when an asteroid collided into our planet sending out large volume of debris that fused into the moon.
The team plans on conducting further analysis that will give them some information on the evolution of organic molecules in the early solar system.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone