Los Angeles:
The actual age of Moon, the natural satellite of the Earth, has been revealed and it is older than previously thought. According to scientists, the Moon is actually 4.51 billion years old which roughly 140 million years old than thought previously.
The age of the Moon was revealed after a study of minerals called zircons. In 1971, the Apollo 14 mission brought back the zircons from the Moon to the Earth.
There has been a hot debate on the age of the Moon, even as the scientists have been trying to settle the question over many years. They have been using wide range of scientific techniques.
"We have finally pinned down a minimum age for the Moon; it is time we knew its age and now we do," said Melanie Barboni, research geochemist at University of California, Los Angeles (UCLA) in the US.
A violent, head-on collision between the early Earth and a "planetary embryo" called Theia, gave birth to the Moon.
The new study would mean that Moon formed "only" about 60 million years after the birth of the solar system. This provides critical information for astronomers and planetary scientists who seek to understand the early evolution of the Earth and our solar system, researchers said.
Barboni said that has been a difficult task because "whatever was there before the giant impact has been erased."
What occurred before the collision with Theja, scientists cannot know, but these findings are important because they will help researchers continue to piece together major events that followed it.
As most of the Moon rocks contain a patch work of fragments of multiple other rocks, it is usually difficult to determine the age of the Moon rocks.
However, Barboni managed to analyse eight zircons in pristine condition.
She examined how the uranium they contained had decayed to lead and how the lutetium they contained had decayed to an element called hafnium.
The researchers analysed those elements together to determine the Moon's age.
"Zircons are nature's best clocks. They are the best mineral in preserving geological history and revealing where they originated," said Kevin McKeegan, a UCLA professor of geochemistry and cosmochemistry.
The Earth's collision with Theia created a liquefied Moon, which then solidified. Scientists believe most of the Moon's surface was covered with magma right after its formation.
The uranium?lead measurements reveal when the zircons first appeared in the Moon's initial magma ocean, which later cooled down and formed the Moon's mantle and crust; the lutetiumhafnium measurements reveal when its magma formed, which happened earlier.
Previous studies concluded the Moon's age based on Moon rocks that had been contaminated by multiple collisions. McKeegan said those rocks indicated the date of some other events, "but not the age of the Moon."
The study was published in the journal Science Advances.
(With inputs from PTI)
