Moon may be younger than thought, study says
An analysis of a lunar rock raises questions about when and how the moon was formed. It may be 200 million years younger than widely believed.
|The moon rises over Los Angeles City Hall. The new analysis could leave scientists who model the moon’s formation “scratching their heads,” said an isotope geochemist who was not involved in the study. (Scott Harrison / Los Angeles Times)
By Amina Khan, Los Angeles TimesAugust 18, 2011
The moon may be 200 million years younger than widely believed, according to a new analysis of a rock brought back to Earth in 1972 by Apollo 16 astronauts. Or, if not, the moon may never have had the magma ocean that scientists think covered its surface soon after it formed.
Either way, the findings published online Wednesday by the journal Nature could send lunar scientists back to the drawing board to reconsider the moon’s evolution.
The moon is thought to have formed from debris ejected into space after a Mars-sized body collided with the still-molten Earth about 4.5 billion years ago. The young moon would have been hot and blanketed by magma. But without a thick atmosphere to trap its heat, the molten rock cooled relatively quickly, while minerals that were less dense than the magma floated to the top first, forming the moon’s crust. These rocks give the white highlands of the moon’s near side their pale hue, and have been used to determine the point at which the moon solidified into the body we know today.
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