This little program is a simple illustration of one reason why many people resisted the discovery that the Earth rotates.

The first frame shows what we all see. As Simplicius, a character in Galileo's Dialogue Concerning the Two Chief World Systems puts it, "I am aware of its [the stone's] descent in relation to the tower because now I see it beside one mark on the tower, now at a lower one, and so on successively until I discover it united with the Earth.

The second frame illustrates the objection: "A tower from whose top a rock was let fall, being carried by the whirling of the Earth, would travel many hundreds of yards to the east...and the rock ought to strike the earth that distance away from the base of the tower."

However, as the third frame shows, the stone itself already has the same West to East motion as the tower; we just don't notice it because we are all moving together. This realization causes one of the characters to remark that "straight motion goes entirely out the window and nature never makes any use of it."

At the end, the red stone is not next to the base only because this is, after all, the Leaning Tower of Pisa. The stone does come to rest directly below where it was at the top of the tower.