It is clear that the Earth has grown by adding mass, and not by an expansionary process
of constant mass. This is because there is much evidence to show that Pangaean Earth
has grown from even smaller proportions, and perhaps the Earth was originally as
tiny as Ceres, a planetesimal, only 900 km in diameter.
In the following graph I have put the rocky planet positions as coordinates on a
graph to see if there is a pattern between their distances from the Sun and their
diameters. Although we have only five co-ordinates to work with, a basic profile
becomes evident and it shows that growth from Pangaean Earth (the approximate size
of Mars) to present day Earth was roughly linear. To this linear section of the curve
I have added the various Earth sizes relating to different Geological Periods as
derived by my modelling. I have also inserted a time scale (deduced from the Pangaean
Earth Model) and this allows us to extrapolate back for a time when the Earth was
perhaps as small as Ceres, and forwards to a time when the Earth will be like Venus
and then Mercury.
At a critical distance from the Sun (roughly halfway between Earth and Venus) the
graph suggests that planets begin to progressively diminish in size. I will discuss
the possible reasons for this in another chapter but for now let us continue to examine
a possible mechanism for the planetary growth which has taken place in the last billion
The mass that has been gradually added to the Earth will not have come from the solar
wind which emanates from the Sun, because it comprises only of
A MECHANISM FOR
protons (positively charged hydrogen ions - 89%) and neutrons (helium nuclei with
no charge - 10%).
Because the Earth is built from the range of elements, as described by the Periodic
Table, these could have only come from the cosmos, from outside the solar system,
originally. All the elements above hydrogen and helium were created in the centres
of large stars, or were created when these stars exploded as supernovas. Particles
(stardust) from these massive explosions are fired off into the galaxy and are flung
great distances before the gravitational pull of another star deflects them towards
So imagine some of this stardust cloud entering the solar system. The size of the
particles can vary considerably from just a few atoms to grains about one hundredth
of the width of a human hair (D. Brownlee). There is no overall charge on these particles.
The space ship Ullyses has collected these particles for sampling.