[meteorite-list] NWA5400

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Mon, 11 Mar 2013 12:35:32 -0600
Message-ID: <CADYrzhrYf2X1MT0z_wro5VbrQ0gttM=5jZGcezyhh=5BnyfHCg_at_mail.gmail.com>

Hi Jodie,

My bias is from a planetary differentiation perspective. The only
known meteorites to sample solar system bodies with long-lived (>1 BY)
igneous activity are lunars and martians. The HEDs might be considered
borderline "planetaries", since some cumulate eucrites have slightly
younger ages than 4.5 BY, but that may be from metamorphism rather
than primary igneous activity. So, given my bias, I see all the
"ancient" achondrites as coming from asteroids and the only
"planetaries" (yet known) are lunar and martian. You see, my bias is
such that I consider the Moon to be in the same category as
terrestrial planets, and that it just happens to orbit the Earth. This
is probably not how astronomers see the the solar system, but just
fine for an igneous petrologist!

Best,

Carl

-- 
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
Tel: (505) 750-7172
Fax: (505) 277-3577
Email: agee at unm.edu
http://meteorite.unm.edu/people/carl_agee/
On Mon, Mar 11, 2013 at 12:15 PM, Jodie Reynolds
<spacerocks at spaceballoon.org> wrote:
> Dear Professor Agee,
>
> The IAU's decision to go all rogue on the definition of a "planet,
> dwarf-planet, minor-planet, [iamnotaplanet, iamtooaplanet,
> someplanetnamedstan]" doesn't leave me with a warm and fuzzy about
> calling Earth a planet.  "Cleared our orbit" - I'm not even certain
> that's necessarily the case...
>
> But then, having spent my formative years haunting Lowell
> Observatory, I've got a dog in that fight and I'm pretty compromised
> intellectually/emotionally on the whole topic.
>
> I agree that today the IAU defines 4Vesta as a "minor planet" the
> same as any other asteroid, though it's larger and with more of a
> cleared orbit than Makemake or probably Haumea, both "dwarf planets"
> per the IAU, and not far behind Ceres.
>
> I'm not at all confident the IAU won't change their mind tomorrow** and
> turn it into a "dwarf planet" with the same total lack of regard and
> status as Pluto received.
>
> --- Jodie
>
> ** 4Vesta appears to have far more hydrostatic equilibrium than
> dwarf-planet Haumea, and it appears to have cleared its neighborhood more than any
> of the other "Small Solar System Bodies" excepting Ceres, per Resolution 5A.  Resolution 5B would have cleared
> a lot of that up, but 5A was passed and 5B shot down, go figger, and
> now we need to worry about "trans-Neptunian dwarf planets that aren't
> planets at all but bear the name 'planet'" ;-)
>
>
>
>
>
> Monday, March 11, 2013, 7:41:12 AM, you wrote:
>
>> Hi Pete,
>
>> Aubrites and enstatite chondrites also plot on the oxygen isotope
>> terrestrial fractionation line (TFL) and up to now they are not proven
>> to be from planets. So being on the TFL doesn't make the meteorite
>> planetary. But I guess it depends on your definition of "planetaries",
>> I would only put lunars and martians in that category, but not HEDs.
>> Last time I checked, 4 Vesta the hypothesized HED parent body, was
>> still an asteroid, not a planet. I see no reason to consider NWA 5400
>> "planetary". On the other hand, if someone did an age-date on it, and
>> it came up with a crystallization age much more recent than ~4.5 B.Y.,
>> then things would get interesting. This is because asteroidal
>> achondrites have ages ~4.5 B.Y., whereas planets tend to have younger
>> basalts. Likewise, the search for meteorites from Mercury or Venus
>> should include igneous crystallization ages as part of the "proof".
>
>> Carl Agee
>
>> Carl B. Agee
>> Director and Curator, Institute of Meteoritics
>> Professor, Earth and Planetary Sciences
>> MSC03 2050
>> University of New Mexico
>> Albuquerque NM 87131-1126
>
>> Tel: (505) 750-7172
>> Fax: (505) 277-3577
>> Email: agee at unm.edu
>> http://meteorite.unm.edu/people/carl_agee/
>
>> On Mon, Mar 11, 2013 at 2:20 AM,
>> <pshugar at messengersfromthecosmos.com> wrote:
>>> Since this tracks on the terestial O2 line, can this be concidered a
>>> planetary meteorite, along
>>> with the Lunars, Martians, as well as Asteroid 4 vesta?
>>>
>>> Would these be the only 4 planitaries so far or has maybe Mecrury
>>> checked in with a sample of it's own?
>>>
>>> Pete IMCA 1733
>>> ______________________________________________
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>
>
>
>> --
>
>
>
>
>
> --
> Best regards,
>  Jodie                            mailto:spacerocks at spaceballoon.org
>
>
>

Received on Mon 11 Mar 2013 02:35:32 PM PDT