Geology Reference
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hoping to get a government grant soon with which to buy
others. I feel sure the results will have an important bearing
both on the origin of meteorites and the inner structure of the
Earth.' Alas, Holmes did not get his government grant, over-
taken as he was by global events and the outbreak of the First
World War.
We now know that Chamberlin's Planetesimal Hypothesis
was incorrect with regard to the formation of the Earth. Current
understanding considers that the whole Solar System formed
from a great cloud of gas, most of which collapsed to form the
Sun, leaving a small amount of material behind (about one per
cent) which condensed to form the planets and other extrane-
ous bodies such as moons, asteroids and comets that subse-
quently fragmented to create meteors. (Meteors only become
meteorites when they hit the Earth's surface.) But regardless of
which theory Holmes believed formed the Solar System, in 1912
he recognised that a study of meteorites could hold the key to
understanding the early evolution of the Earth because:
'Meteorites allow us to read at our leisure many of the secrets
which are otherwise locked up in the Earth's interior'. His radi-
um study provided us with the first real indication that the Earth
may have originated from the same material as other extrater-
restrial bodies but, as is often the case, that work lay forgotten
when, over forty years later, the genetic link between the Earth
and meteorites became an issue of major importance.
As you look up to the stars tiny photons of light that have been
travelling through space, perhaps for millions of years before
you were born, find a resting place in your eyes. Everything that
has ever happened in the world, the solar system and the
Universe, has occurred in its own time and place just so that that
particular photon can reach you at that precise moment in time,
millions of light years after it left its point of origin. The longer
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