Page "Aberration of light" Paragraph 20

As early as 1573, Thomas Digges had suggested that this theory should necessitate a parallactic shifting of the stars, and, consequently, if such stellar parallaxes existed, then the Copernican theory would receive additional confirmation.

Many observers claimed to have determined such parallaxes, but Tycho Brahe and Giovanni Battista Riccioli concluded that they existed only in the minds of the observers, and were due to instrumental and personal errors.

In 1680 Jean Picard, in his Voyage d ’ Uranibourg, stated, as a result of ten years ' observations, that Polaris, or the Pole Star, exhibited variations in its position amounting to 40 ″ annually.

Some astronomers endeavoured to explain this by parallax, but these attempts were futile, for the motion was at variance with that which parallax would produce.