SpaceWatchtower: New Info on Moon Age, Origin May Help Solve Mystery

Thursday, April 3, 2014

New Info on Moon Age, Origin May Help Solve Mystery

http://grin.hq.nasa.gov/IMAGES/SMALL/GPN-2000-001046.jpg

Moon setting as viewed from Earth orbit. (Image Source: NASA)

By Charles Q. Choi, Space.com Contributor

Scientists have pinned down the birth date of the moon to within 100 million years of the birth of the solar system — the best timeline yet for the evolution of our planet's natural satellite.

This new discovery about the origin of the moon may help solve a mystery about why the moon and the Earth appear virtually identical in makeup, investigators added.

Scientists have suggested the moon was formed 4.5 billion years ago by a gigantic collision between a Mars-size object named Theia and Earth, a crash that would have largely melted the Earth. This model suggested that more than 40 percent of the moon was made up of debris from this impacting body. (Current theory suggests that Earth experienced several giant impacts during its formation, with the moon-forming impact being the last.)

However, researchers suspected Theia was chemically different from Earth. In contrast, recent studies revealed that the moon and Earth appear very similar when it comes to versions of elements called isotopes — more so than might be suggested by the current impact model. (Isotopes of an element have differing numbers of neutrons from one another.)

"This means that at the atomic level, the Earth and the moon are identical,"study lead author Seth Jacobson, a planetary scientist at the Côte d'Azur Observatory in Nice, France, told Space.com. "This new information challenged the giant impact theory for lunar formation."

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Source: Space.com .