Hi, Chris, List,
Well, Venus is shrouded in doubts on hundreds
of details. Yes, the core could be "frozen," but it would
require Venus to be of radically different composition
than the Earth. If the Earth rotated once every 224.7
days, as Venus does, instead of once every 24 hours,
I doubt we'd detect much of a planetary magnetic
field from space probes around the Earth either.
The Russian probes (at least Venera 13 and 14) had
geophysical instrumentation that was able to determine
the bulk composition of those bare black basaltic-looking
rocks the probes sat down on, every though they had only
13-16 minutes to do so before the electronics fried. And
that basalt-looking stuff seems to be... basalt. The bulk
composition figures returned could be any of thousands
of basaltic regimes on Earth -- no unusual features of
any kind whatsoever. Boringly similar to Earth.
Sterling K. Webb
-----------------------------------------------------------------------------------
----- Original Message -----
From: "Chris Peterson" <[email protected]>
To: <[email protected]>
Sent: Saturday, September 05, 2009 11:33 PM
Subject: Re: [meteorite-list] Slow cooling rate of irons in space
Hi Sterling-
From what I've read, there is actually a fair bit of doubt that Venus
has a
molten interior. The only reason to think it does is because of its
similarity to Earth (in terms of size and density). But there's a lack
of good understanding about formation details (such as isotope types
and amounts), so quite a few planetary geologists (silly term, isn't
it?) consider it very possible that the core of Venus froze a long
time ago.
In any case, more information is needed. And the fact that Venus has a
weak magnetic field doesn't mean it necessarily has a solid core
(although that remains an important piece of evidence in favor of that
scenario); core dynamos aren't well enough understood to know if a
molten core always produces a magnetic field.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message -----
From: "Sterling K. Webb" <[email protected]>
To: "Rob McCafferty" <[email protected]>;
<[email protected]>
Sent: Saturday, September 05, 2009 10:21 PM
Subject: Re: [meteorite-list] Slow cooling rate of irons in space
Hi,
Venus they're not sure about.
One thing I think we can be sure about is that
no one will ever use the phrase "so darn cold"
about Venus, as we stand next to a small creek
running with liquid lead and other low melting
point metals...
There are signs that may be recent activity on
Venus in some areas, but interpreting them
is in dispute. Generally, the surface of Venus
appears to have formed all at one time, crater
dated at 480 +/- 80 million years ago. The lack
of long-term change is attributed to the fact
that Venus's crust is, compared to the Earth's,
extremely thick and rigid, with no detectible
tectonic movement, recent mountain building,
or any of the other features of a "terrestrial"
planet. But, given the similarity in size, density
(and hence composition) to the Earth, few doubt
that Venus' core is as hot and active as our own.
It's just that nothing (much) can punch its way
through that heavy crust.
______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
[email protected]
http://six.pairlist.net/mailman/listinfo/meteorite-list
______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
[email protected]
http://six.pairlist.net/mailman/listinfo/meteorite-list
