[meteorite-list] Earth's Surface Transformed by Three MassiveAsteroid Imp...

From: MexicoDoug_at_aol.com <MexicoDoug_at_meteoritecentral.com>
Date: Fri Aug 5 23:00:01 2005
Message-ID: <1e1.41fdf4ca.3025818f_at_aol.com>

Hola Tracy, since moon rocks are up to 3.8 or 4.0 billion years old or maybe
someone can correct that upward, the theory it is commonly "over 4 billion
years ago". I don't know if more precision is available, but the crust would
have formed after the collision so we are looking at after Earth formation,
say 4.4 billion years ago, to before Moon crust formation 4.0 billion years.
Averaging it out for no particular reason give 4.2 billion years ago for the
Moon coalescence - plenty before 3.2 billion years, though who knows about
"over 3.2 billion years" referenced in the news-short, at first glance...
Saludos, Doug

Tracy L. wrote:
>Someone please refresh my memory -- about how long ago was the theorized
>impact that tore loose the Moon from the proto-Earth? This sounds like it
>happened after the Moon had coalesced enough to be a single solid.

>Tracy Latimer

>From: Ron Baalke <baalke_at_zagami.jpl.nasa.gov>
>To: meteorite-list_at_meteoritecentral.com (Meteorite Mailing List)
>Subject: [meteorite-list] Earth's Surface Transformed by Three
>MassiveAsteroid Impacts 3.2 Billion Years Ago
>Date: Fri, 5 Aug 2005 11:47:36 -0700 (PDT)
>
>
>http://info.anu.edu.au/mac/Media/Media_Releases/_2005/_August/_050805glikson.
asp
>
>Earth's surface transformed by massive asteroids
>Australian National University media release
>August 5, 2005
>
>A cluster of at least three asteroids between 20 and 50 kilometres
>across colliding with Earth over 3.2 billion years ago caused a massive
>change in the structure and composition of the earth's surface,
>according to new research by ANU earth scientists.
>


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Received on Fri 05 Aug 2005 10:59:27 PM PDT