Re: "Sagan and Velikovsky" to appear in local book stores
Andrew MacRae (macrae@geo.ucalgary.ca)
25 Jan 1995 20:25:15 GMT
Followups set to talk.origins. Please take discussion there.
In article <3g4pbo$168@no-names.nerdc.ufl.edu> kennedy@quark.phys.ufl.edu
(Dallas Kennedy) writes:
> The main conventional book on Venus I was thinking of, was _Venus_,
> published by U. Arizona Press in 1983 [?]. It uses the Pioneer and
> Venera data, but clearly not the Magellan data.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> One item that is clear from that book is that Venus is not in thermal
> balance; that is, its heat out flux (157 W/m^2) is larger than its light
> in flux (106 W/m^2), after the albedo (0.84) is taken into account. The
> chapter in the book that deals with this concludes that there "cannot"
^^^^^^^^
> be an internal heat source, so it just ad hoc changes the albedo to
^^^^^^^^^^^^^^^^^^^^^^^^^^^
> adjust the heat budget into balance.
Uh, yeah. There "cannot be an internal heat source". At least,
that was fairly clear in 1983 (because the heat required was orders of
magnitude higher than the internal heat production on Earth, and that
seemed unlikely), and that is what the Magellan data clearly indicates now
(there isn't a big internal heat source). If there is a way there can "be
an internal heat source", no one has explained how in a way that is
compatible with the available evidence. Venus does not even appear to be
as geologically active currently as the Earth currently is.
I am not saying the data involving thermal balance is arbitrarily
wrong, I'm just saying no plausible explanation has been offered for its
occurrence if you assume it is right.
..
> even about equal to the equatorial temperatures. From this, I infer
> that the dominant heating at Venus' surface is not solar, but internal.
On the Earth, the solar input outweighs "internal", geological
sources by several orders of magnitude. This should give you an
impression for the sort of geological output required on Venus -- huge.
>(3) Venus has a youthful-looking surface, not gnarled and wrinkly like
> the Earth's :)
"Youthful-looking" because it is not "gnarled and wrinkly like the
Earth's"? That is the most bizarre dating method I have ever heard of,
and parts of Venus are "gnarled and wrinkly". The surface of the Earth is
being continually modified by plate tectonics and erosion. 70% of the
Earth's crust is oceanic, and is less than about 160 million years old.
The remaining continental surface is composed of rocks that are much
older, but their *surface* is quite young because it is being actively
eroded. Craters, for example, do not preserve well or for long on the
surface of the Earth relative to Venus. The surface of Venus is, on
average, older and less modified than the Earth's.
Take a look at:
Kerr, R.A., 1994 (February 11). A new portrait of Venus:
thick-skinned and decrepit. Science, v.263, p.759-760.
>
> How the planet science community could have kept up the greenhouse
> model, especially with no inverted temperature gradient, is bizarre. I
> assume it is by inertia or politics.
How the Velikovskian community can continue to claim the data from
Venus supports an internal, geological heat source to explain the "thermal
imbalance" is bizarre. No, wait, it isn't that bizarre. They just cite
literature predating Magellan, or take a first glance at the data and say,
(in Homer Simpson style) "Hmmmmmmm.... volcanoes."
--
-Andrew
macrae@geo.ucalgary.ca
home page: "http://geo.ucalgary.ca/~macrae/current_projects.html"
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