Stand up. Take a few paces around your home, the tea house, the park, wherever you happen to be. Sip on your tea. Do you feel the Earth moving? Is the Earth moving? All of us today will scoff and say of course the Earth moves. In fact, we know it moves quite fast: it orbits the sun at 67,000 mph and rotates on its axis 1,037 mph at the equator (space.com How Fast the Earth is Moving). However, put yourself in the shoes of someone just 400 years ago when this information was not common knowledge. What would you think? Does your day-to-day experience support these facts?
Geocentric Model
Over 400 years ago, when a person looked up at the stars, they believed they were glimpsing at the heavens. Every day they would see the sun rise in the East and set in the West. Every night they observe the moon rise and bright stars move across the dark sky. These observations gave birth to the geocentric model of the solar system with the Earth resting at the center and all other celestial bodies rotating about in perfect circles.
“In the heavens, it was believed there must be eternal perfection, and what more natural and beautiful a representation of eternity could one have than ceaseless motion in the most perfect of figures, the circle?”
Relativity and Its Roots by Banesh Hoffmann
It is sometimes strange to think that this geocentric model has dominated the beliefs of humans much longer than the heliocentric model. To this day we still use geocentric language when we talk about “sunrise” and “sunset” which implies the Sun revolves around the Earth.
Heliocentric Model
The Heliocentric Model gained popularity during the “Copernican Revolution”. Despite what is implied by the revolution’s title, there were several key players over a long time period that eventually turned mankind’s beliefs closer to the truth of the universe.
Nicolaus Copernicus (1473-1543)
While Copernicus was not the first person known to suggest the Heliocentric Model, he expressed his beliefs with the backing of mathematical rigor that eventually led to the model’s acceptance. He would pass before the heliocentric model dominated.
Johanes Keppler (1571-1630)
Keppler used the meticulous astronomical observations of Tycho Brahe to discover three laws of planetary motion:
- The planets orbit in an elliptical path with the sun as a focus point of the ellipse.
- The closer a planet gets to the sun the faster it moves.
- The time a planet takes to orbit the sun is related to the distance the planet is away from the Sun.
Galileo Galilei (1564-1642)
Galileo did not discover the telescope. However, when he heard of the invention, he built his own and was the first to turn it towards the heavens for the purpose of study. Galileo looked through the lens of his DIY telescope and discovered hills and valleys on the moon, sunspots on the sun (he eventually went blind probably partly due to this discovery—don’t stare at the sun!), Jovian moons around Jupiter, and the phases of Venus. All of these observations attested to the imperfections of the heavens and supported Copernicus’s Heliocentric Model. Eventually, Galileo published these finding in a book written for the public to enjoy. When the Church heard of Galileo’s book, they put him on trial in front of the Inquisition. Unwilling to yield on his beliefs, Galileo was sentenced to house arrest for the rest of his life.
In short, the universe does not revolve around you. The abolishment of the geocentric model has perhaps humbled the human race a bit. Today, we know that the mysteries of our world will eventually be explained by science and that our planet is special but is not located at the center of the universe.
Sources
Relativity and Its Roots by Banesh Hoffmann
Inside Relativity by Thomas Vargish & Delo E. Mook
How Fast the Earth is Moving by Elizabeth Howell from Space.com
The Theory of Relativitea 