"There is talk of a new astrologer who wants to prove that the earth moves and goes around instead of the sky, the sun, the moon, just as if somebody were moving in a carriage or ship might hold that he was sitting still and at rest while the earth and the trees walked and moved. But that is how things are nowadays: when a man wishes to be clever he must . . . invent something special, and the way he does it must needs be the best! The fool wants to turn the whole art of astronomy upside-down. However, as Holy Scripture tells us, so did Joshua bid the sun to stand still and not the earth."
- Martin Luther, 1539
Thought Experiment: Imagine going outside at sunrise on a clear day and sitting facing the south. Observe the Sun move across the sky until it sets. Also observe no apparent movement of Earth during this time. For example, you may observe the absence of a perpetual wind indicating that you are moving, and a ball thrown straight up into the air doesn’t land behind you. The most obvious conclusion: the Earth is stationary and the Sun (and other planets and stars) move around Earth! Right?
|“eppur si muove” - Galileo?|
Every sunbather or person trying to stay in the shade has made this type of direct observation on their own, but three quarters of Americans think a heliocentric model of our solar system is true - with elliptical rather than circular orbits for the more savvy among us...acknowledging also, if necessary, that the focus of our orbit is not the Sun but the barycenter of the Solar System, which also orbits the Milky Way, yada yada. Or to put it more technically, most of us think that there is no inertial reference frame in which the Earth is stationary at the center and the Sun moves in a circle around it. But why is this counter-intuitive (and Biblically contradicted) fact about our world so widely accepted today? Do you just believe it because that's what you were told? What evidence confirms it?
"I want to argue that clear thinking, combined with a respect for evidence — especially inconvenient and unwanted evidence, evidence that challenges our preconceptions — are of the utmost importance to the survival of the human race in the twenty-first century, and especially so in any polity that professes to be a democracy."
- What evidence convinces you that Earth moves relative to the Sun?
- What evidence supports the idea that Earth is spherical v. flat?
- What evidence supports the idea that the stars are much further away than the Sun, Moon, and other planets?
In hindsight, these are the main lines of evidence that are usually offered to directly support heliocentrism today:
"It is important to note that well-tested theories in the mature sciences are supported in general by a powerful web of interlocking evidence coming from a variety of sources."
References: Heliocentrism & the Copernican Revolution
Primary Historical Sources:
- Nicolaus Copernicus. On the Revolutions of the Heavenly Spheres. 1543.
- Johannes Kepler. The New Astronomy. 1609.
- Galileo Galilei. Dialogue Concerning the Two Chief World Systems. 1632.
- Khan Academy: INTERACT: Models of the solar system
- The Physics HyperTextBook: Heliocentrism.
- Sean Carroll. Does the Earth Move Around the Sun? October 3, 2005. Cosmic Variance blog.
- Phil Plait. Geocentrism? Seriously? September 14, 2010. Bad Astronomy blog.
- Ethan Siegel. Geocentrism: Was Galileo Wrong? September 13, 2010. Starts With a Bang blog.
Modern Philosophy & History:
- Thomas Kuhn. The Copernican Revolution. 1957.
- John S. Wilkins. The Renaissance Mathematicus blog.
- Galileo's great bluff and part of the reason why Kuhn is wrong. November 10, 2010.
- The Tycho Myth. November 13, 2012.
- Beware of hindsight. April 30, 2014.
- The Phases of Venus and Heliocentricity: A Rough Guide. June 9, 2014.
- The Transition to Heliocentricity: The Rough Guides. June 20, 2014.
- Rob Boston. Self-Centered: 'Geocentrist' Movie To get Limited Theatrical Release. June 6, 2015.