On the surface, The Principle looks like it might be an interesting science documentary: Speakers featured in the trailer include physicists and science educators Lawrence Krauss and Michio Kaku, and the film is narrated by Kate Mulgrew, who played Captain Janeway in Star Trek: Voyager, and more recently, Red in Orange is the New Black. But not far below the surface lies a load of bullshit.
The producers are Robert Sungenis, a Holocaust denier and advocate of geocentrism, and Rick DeLano, who believes no experiment can measure the motion of the Earth around the sun. DeLano says the film “is not about geocentrism per se,” but aims to question the Copernican Principle – which states that the Earth is not in a central, specially favoured position in the universe – while including historical facts about geocentric cosmology and the “seemingly conclusive establishment of the heliocentric model of reality.” That sounds to me like it is a film about geocentrism.
Shortly after the trailer was released, Mulgrew published a statement distancing herself from the project, stating she was “a voice for hire, and a misinformed one at that,” and Lawrence Krauss said the clips of him were either taken from existing interviews, or the filmmakers interviewed him under false pretenses.
In Krauss’s essay for Slate titled “I Have No Idea How I Ended Up in That Stupid Geocentrism Documentary,” he suggests we not talk about the film at all: “The best thing we can all do when faced by nonsense like that, or equivalent silliness promoted by biblical fundamentalists who claim that science supports a literal interpretation of the Bible, is to ignore it in public forums, and not shine any light on the authors of this trash,” he said.
So let’s focus on a more interesting question: How do we know the Earth revolves around the sun?
The answer is not as simple as you might think, says Stan Shadick, sessional lecturer in astronomy with the physics and engineering physics department at the University of Saskatchewan.
“I challenge my students to tell me why the Earth goes around the sun, and I won’t accept the answer that my high school teacher told me it does,” he said.
There are several reasons why we know the Earth is moving around the sun, but the easiest to explain is stellar parallax.
You can do an experiment right now to understand parallax: Hold your thumb up in front of you at arm’s length, then close first the left eye, and then the right eye. You’ll find that the thumb seems to shift its position. The closer you move your thumb to your eyes, the bigger the shift seems. This difference in the apparent position of an object viewed along two different lines of sight is parallax.
The same shift can be seen in a star viewed from the Earth at different points in its path around the sun, says Shadick.
“If the Earth is moving through space, our view of a star in January should be in a slightly different direction than in July because we’re viewing it from a different location.”
The farther away the object is, the more subtle the shift, and it turns out, even the closest extrasolar star is very, very far away (that would be Proxima Centauri, which is over 40 trillion kilometres from Earth). The stellar parallax is so subtle, it can only be seen with a telescope.
The first person to measure the phenomenon was Friedrich Bessel in 1838, but the effect was theorized long before then. In fact, in the 1500s, Tycho Brahe tried to find the stellar parallax, but failed. James Bradley tried again to find the stellar parallax in 1729; he also failed, but he found the first proof we had that the Earth moves around the sun: stellar aberration.
Abberation of starlight is a bit more complicated to explain than stellar parallax. A Cornell University website gives the abbreviated definition as “a slight change in stellar positions due to Earth’s speed.” The Doppler effect also proves that the Earth is moving, producing very tiny shifts in color of stars. If you’re interested in learning more, there’s this great thing called the Internet; I hear they even let you use it for free at the library.
It’s easy to understand why ancient civilizations believed the Earth was the centre of the universe: If you look up at the sky, the rotation of the Earth makes it appear as though the sun, moon, and stars are moving across the sky. It’s not easy to understand why Sungenis and DeLano took so much time, money, and effort to create a documentary that can be disproved by a quick online search for “Does the Earth orbit the sun?”
This article was originally published on the Prairie Dog blog on 15 May 2014.