Re: A big whack that made the moon may have also created continents that move

In alt.astronomy a425couple <[email protected]> wrote:
> A big whack that made the moon may have also created continents that move
> 
> June 19, 2024 at 11:31 am
> A rendering of Earth&#8217;s collision with a Mars-size planetary object 
> called Theia 4.44 billion years ago. Computer simulations suggest that a 
> collision with another planetary object early in Earth???s history may 
> have provided the heat to set off plate tectonics. (Hern??n Ca??ellas via 
> The New York Times)
> 
...

An interesting idea.

The numbers in this area are pretty big.

Planetary tidal heating (the monn and Jupiter are about 1/2 ea)
totals 60 TJ.

All the mag5+ quakes in a year totals around 600 TJ.

Tectonic activity -- all the heat coming out of the planet
from radioctive decay mostly -- amounts to around 1 billion TJ/yr.

That sounds like a big number until you think of how much sun
hits the earth in a year. About 8e12 TJ.
(Just the pissweak part of that contributed by burning fossible
fuels is only 1e10 TJ/yr).

But this all PALES in comparison with how much energy is available
for one orbiting body to slaughter another.

It's kinda a theorem of orbital disaster mechanics that the average
approach speed of 2 objects in approx the same orbit is the
average orbital speed. In the case of the earth and a similar-sized
planet orbiting the sun in similar orbits that is around 1e19 TJ.
I.e. the equivalent of around 1e10 years of tectonic activity.

Yea. That would heat things up real good. ;)