Note 113 — Chapter II · Copernicus and His Times.

As the earth moves, the position in the heavens of a fixed star seen from the earth should differ slightly from its position observed six months later when the earth is on the opposite side of its orbit. The distance to the fixed stars is so vast, however, that this final proof of the earth's motion was not attained till 1838 when Bessel (1784-1846) observed stellar parallax from Königsberg. Berry: 123-24.