Why doesn our Moon spin on its axis ( rotates ) like the moons of Jupiter and Saturn?
Answer Our Moon does rotate. It just rotates synchronously — that is, it rotates once, each time it goes around us. Its rotation period is 27.3 days, and so is its orbital period. So when it goes 1/4 or 1/2 or 3/4 of the way around us, it rotates 1/4 or 1/2 or 3/4 of the way around its axis. The result is that it always keeps the same face to us; but the stars move westward across its sky, once every 27.3 days. To visualize this, take two balls, one representing the Earth, and the other the Moon. Paint one side of the “Moon” differently from the other, so you can tell which side it is. Let’s call that the “near” side (in fact, you might just paint “NEAR” on it). Now stand so that the NEAR side of the “Moon” is facing the “Earth”, and also some distant point (a wall behind the Earth, in a room; a distant tree or some such, outdoors). Walk around the Earth, keeping the “Moon” always facing the same way (toward the wall or tree, as it originally faced). If you do that, the “NEAR” side of
