On Sunday, August 20, 2000 12:19 PM Robert J. Bradbury bradbury@aeiveos.com
wrote:
> > Now, any excess heat a planet radiates above that which it receives from
> > the sun is obviously a result of it turning its angular velocity to heat
> > through vulcanism in Venus's case (it doesn't have much angular
> > velocity, having a retrograde day of some 240 earth days) and through
> > convection in the case of Neptune. Unless you think there are Helium3
> > people living on Neptune fusing hydrogen for energy...
>
> Actually, the latent heat of planet formation seems to still be
> the driver for most of the gas giants (esp. Jupiter). The insulating
> layer accumulates relatively fast and the gradual gravitational
> contraction produces heat that only slowly escapes. There is
> also a fair amount of radioactive material gradually decaying.
This is my understanding.
> I don't think the equations of state are well enough understood
> to predict how much heat should be produced by these effects
> and the rates at which they should escape through the overlying
> material. For example, we can barely make solid-metallic hydrogen,
> and can't yet measure such properties as electrical or heat conductivity
> effectively). I think the jury is still out on whether Mars does
> or does not have a liquid core. And Mars is relatively easy compared
> with the gas giants.
True. I think given the low magnetic activity though, we can guess which
verdict the jury is going to pick.:)
> But, I would agree the EvMick's quote of Venus radiating 40x its solar
> input is higher than anything I've ever seen. Its albedo is very
> high, reflecting away much of its incoming light. The high
> CO2 concentration in the atmosphere is required to create the
> very high surface temperatures. Unless someone is running a
> large number of nuclear reactors on the surface, the 40x figure
> is dubious.
I doubt the figure too, though the surface rock is almost at a liquid state.
In fact, some believe that Venus goes through a cycle of complete meltdowns
where the crust and mantle are mixed. The cycle length is estimated to be
about half a billion years based on the lack of surface features that seem
older than that.
So, perhaps heath from Venus' innards makes it out much more quickly than
Earth's.
Cheers!
Daniel Ust
http://uweb.superlink.net/neptune/
This archive was generated by hypermail 2b29 : Mon Oct 02 2000 - 17:36:20 MDT