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Where does the Mass come from?

 

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 years.

 

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

61

A MECHANISM FOR

PLANETARY GROWTH

 

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 it.

 

 

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.

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