🚀 go-pugleaf

bscott@lyman.pppl.gov (Bruce Scott) writes:

> Actually, one important reason why people turned against the exploding
> planet hypothesis was the discovery that certain classes of asteroids
> have compositions which are not consistent with any scenario which
> involves heating above 300 K.

     The most common type of meteorite, chondrules, are partially melted
rocks, where the melting occurred well before atmospheric entry.  It is
true that *certain* classes of meteorites have apparently never been hot.
But a planetary explosion would have vaporized core material, melted
intermediate material, and simply fractured the outer mantle and crust.
Meteorites from this last class would have been propelled far away before
they could be heated significantly (as Leigh Palmer also suggested).

> This and the fact that the property classes (achondrite, C1 and C2
> chondrite, enstatite, etc) are on isotopic grounds irreconciliable with
> any single parent body are the reasons J S Lewis argues against it.

     That argument has always seemed a bit of a non-sequitur to me.  If (in
the standard model) all the asteroids and meteorites had condensed into a
planet instead of going their separate ways, then the single parent planet
would have been isotopically diversified.  But chiefly, one must expect
that most isotopic anomalies originated in the intense irradiation event
that accompanied the explosion.  There is ample meteoritic evidence for
this irradiation event.

     One should also note that the exposure ages of meteorites neatly
define just the ways such materials would be layered in a planet.  For
example, the heavy iron meteorites came from farthest in, and have the
greatest "cosmic ray" exposure ages; and the lightest, most "primitive"
meteorites, presumably from near the planet's crust, have the smallest
exposure ages.

> A chemical explosion strong enough to break up a massive body? I've
> never seen a plausible scenario for this. I won't work out energy per
> gram versus self-gravity energy now, but it seems that the usual
> chemical explosive stuff is too weak for this (unless one had a pure
> liquid gasoline planet well-mixed with oxygen!).

     It all depends on the size of the hypothetical planet.  If it is to
be Saturn-sized, as Ovenden proposed, then no chemical-energy process is
sufficient to overcome self-gravitation.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.