First Move, Copernicus

Nowadays, all of us who are taught the history of science learn that Nicolaus Copernicus, in 1543, put the sun at the universe's center and demoted Earth into just another planet. As far as astronomy goes, that's true. But Copernicus himself meant something quite different, and profoundly geological. Consider the very first sentence of his Revolutions of the Heavenly Bodies, dedicating the book to Pope Paul III: "I can easily conceive, most Holy Father, that as soon as some people learn that in this book which I have written concerning the revolutions of the heavenly bodies, I ascribe certain motions to the Earth, they will cry out at once that I and my theory should be rejected." Elevating Earth from the universe's dregs, a fixed dead zone, into a mobile body exactly on a par with the heavenly planets—turning Earth itself into a planet—was his most profound scientific breakthrough. The idea that Earth was demoted by being pushed out of its central place has been called "the Copernican cliché" by historians of science.

In the March 2010 issue of Geology, Walter Alvarez and Henrique Leitão described this key point of the "Copernican revolution" and urged that geologists claim it as part of their own history. The heliocentric theory that Copernicus is usually lauded for is actually a failure, they said—the sun is not the center of the universe any more than Earth was. But, they pointed out, "the planetary-Earth concept was correct; there has never been any serious reason since then to think that Earth is not a planet."

Geology stands taller in intellectual history than most people think. It is the historical wellspring of physics and chemistry, not some lesser "applied" branch of those fields. And geology provided Darwin's strongest evidence for biological evolution in the years before genetics was well understood; even today fossils are essential to evolutionary research. And today, as astronomers uncover thousands of planets around other stars, they find themselves in deep conversation with (that's right) geologists.

Background:
"Earth" versus "the world"
Earth in the 1600s
Geology and evolution