 Again, Copernican heliocentric astronomy was born “refuted” because of the apparent non-existence of stellar parallax. If the earth goes round the sun then the apparent position of at least some of the fixed stars (namely the closest ones) ought to vary with respect to the more distant ones as the earth is moving with respect to them. Some parts of the night sky should look a little different at perihelion (when the earth is furthest from the sun) from the way that they look at aphelion (when the earth is at its nearest to the sun, and hence at the other end of its orbit). But for nearly three centuries after the publication of Copernicus’ De Revolutionibus 1543, no such differences were observed. In fact, there is a very slight difference in the apparent positions of the nearest stars depending on the earth’s position in its orbit, but the difference is so very slight as to be almost undetectable. Indeed it was completely undetectable until 1838 when sufficiently powerful telescopes and measuring techniques were able to detect it, by which time the heliocentric view had long been regarded as an established fact. Thus astronomers had not given up on either Copernicus or his successors despite this apparent falsification.