[meteorite-list] Lunar capture theory

From: Tom aka James Knudson <knudson911_at_meteoritecentral.com>
Date: Thu Apr 22 10:21:02 2004
Message-ID: <00bb01c347ed$c5e2c420$17c743d8_at_malcolm>

Hello Robert and list, My understanding of planet formation in a nutshell is
that debris orbiting the Sun gradually merged and formed planets. Right?
  Why couldn't two bodies have formed from the same debris in the same
orbit and orbiting around the sun together in the same direction and the
same orbit, Gradually the Moon slowly caught up with the earth and got
caught up in the earths gravity? Or the earth came up behind the Moon and
captured it?

Thanks, Tom
Peregrineflier
The proudest member of the IMCA 6168
----- Original Message -----
From: Matson, Robert <ROBERT.D.MATSON_at_saic.com>
To: meteorite-list <meteorite-list_at_meteoritecentral.com>
Sent: Friday, July 11, 2003 1:01 PM
Subject: [meteorite-list] Lunar capture theory


> Tom wrote:
>
> > I do not believe the moon was made by a asteroid impact on the
> > earth.
>
> What, specifically, about this theory bothers you?
>
> > I would first stand by the theory that it was caught up in our
> > gravity.
>
> While this is a ~possible~ scenario, you have to understand how
> extremely unlikely graceful capture is compared to impact.
> The capture idea also has a difficult time explaining why the
> Moon doesn't have a normal-sized core for a body of its size,
> which the impact theory explains nicely. Finally, why the
> oxygen-isotope similarity of earth and the Moon if the two
> bodies formed in different parts of the solar system?
>
> Prior to the Apollo sample return missions (and the discovery
> of our beloved lunar meteorites), the capture theory at least
> had some wobbly legs to stand on. But O-isotope analysis of
> the moon rocks knocked one leg out, and the other leg was swept
> away by Lunar Prospector's confirmation that the moon's core
> comprises less than 3% of the moon's mass.
>
> --Rob
>
>
>
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Received on Fri 11 Jul 2003 04:48:22 PM PDT