The Year Everything Changed

This year has been declared by the United Nations as the International Year of Astronomy. 400 years ago, in 1609, Galileo Galilei turned his crude telescope to the sky, saw the mountains and craters of the Moon, the phases of Venus and the moons of Jupiter and from that moment on, nothing was ever the same.

Before Galileo, it was a widely held belief that the Greeks were the highpoint of knowledge, civilization and culture and it was pretty much all downhill from there. And the Greek notions of how the world worked were held to be the final word on science and mathematics.

The Greeks held peculiar notions about our world. The Earth was made up of Fire, Air, Water and Earth. The four elements were in a constant tug of war – fire and air to push up and water and earth to pull down – resulting in our imperfect, flawed Earth.

The Heavens were held to be perfect. Made up of quintessence, or the heavenly essence. The Moon, Sun, Planets and Stars moved about us in orbits perfectly circular. The Moon and Sun were perfect spheres (the markings on the Moon were believed to be an obstruction from the imperfect air about the Earth). The heavens and the Earth were held to be very different from each other.

To the medieval mind, in the age of wars, plagues and famine, the notion of a small, perfect Universe with God in his perfect Heaven watching from above, must have been especially comforting. By the beginnings of the time we now call the Age of Enlightenment, the Geocentric model of the Universe, as expounded by Ptolemy in the 2nd Century, was showing its age.

: Image via Wikipedia

If you spend enough time under the night sky, the limitations of the Ptolemaic / Geocentric view will become apparent. The retrograde motion of the outer planets in their orbits, the fact that the inner planets (Mercury and Venus) don’t go across the sky like the rest of the heavenly population but instead transit back and forth around the Sun. All of this pointed to a different model – the Heliocentric model of a solar system with the Sun in the middle and the planets in their orbits around it.

Nicolaus Copernicus was the first scientist to espouse the Heliocentric view, but it took Galileo to prove it with his observations. And in the process, Galileo created the modern scientific method, where evidence and experimentation replaced superstition, wishful thinking and and slavish deference to the past.

Galileo offered his proof of the motion of the Earth around the Sun and dared the scientific, political and religious establishment of his day to prove him wrong – not by pointing to the bible and Aristotle but with empirical evidence derived from observation and experimentation.

By doing so, Galileo brought us out of the darkness of ignorance and superstition and created the modern world.

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