© 1999 Norm Sperling, originally published in *Bay Area Skeptics Information Sheet,* vol. 17, no. 7, May 1999, 2.

Soon after Nicholas Copernicus published his great book De Revolutionibus in 1543, he died. This prevented the Catholic Inquisition from punishing him for his heresy in moving Earth out of the center, and making it merely one planet among many orbiting the Sun.

Copernicus's Sun-centered system came somewhat closer than anything Ptolemaic to predicting planet positions in the sky. While Copernican predictions were noticeably closer, they were still not exact. We now know the big problem was the shape of the orbits: Copernicus clung to the ancient presumption that orbits must be "perfect" circles. They aren't, but nobody knew that in the 1500s.

Though the Roman Catholic Church emphatically denied Copernican theory - even placing it on its Index of Prohibited Works from 1616 to 1835 - they did permit using it as a handy-dandy computing technique for improved results; it simply must not be taught as "true". 'Go ahead and compute that way to get the best results, but don't believe the system.'

With 20/20 hindsight, some academics have snickered at this, because we know the Earth is not the center of everything. But carry the story a few chapters further:

* Tycho makes the sharpest positional measurements,

* Kepler determines from those that orbits are ellipses, and

* Newton derives Kepler's Laws from his own Law of Universal Gravitation.

* Centuries later, Einstein overthrows Newton, regarding gravity as warps in space-time.

To calculate the path of anything moving many percent of the speed of light requires Einstein's equations; that's how they found out that Newton was wrong. But almost everything that astronomy deals with moves less than 1% of the speed of light. At such slow speeds, the numbers from calculating Einstein's formula are identical with the numbers from calculating Newton's simpler formula. So, even now, practically everybody calculates with Newton's formula, and reserves Einstein's more complicated version for the rare cases where things move really fast. They know Newton is physically wrong, they just use it as a simpler way to compute and get the same result.

What these modern astronomers do is little different from what the Church advocated centuries ago: go ahead and use the handiest formula that gives the best result, but don't believe that it is physically true. To be fair, they should stop snickering at that old Church policy, or start snickering at themselves.