Away: "In fact, Galileo had a correct intuition, but a rather weak empirical case. For example, a cornerstone of his argument for heliocentrism was his theory that the rotation of the earth causes the tides in the same way that spinning a bucket causes water inside it to rise up its sides. However, today we attribute tides to the gravitational influence of the moon. Somewhat disturbing to the image of Galileo as the great empiricist is the reliance of his theory on a 24-hour period for the tides, since their period is actually 12 hours. When Galileo was informed that sailors in the Mediterranean were quite certain high tide came twice, not once, per day, he dismissed the discrepancy as being due to local variations in the ocean floor."