[Dacula]

The moon orbits and rotates, right?

[Lonesome in Massachussets]

The moon is "tidally locked" in its orbit around the earth. On average, it rotates at the same rate at which it orbits, so that it mostly keeps the same face towards the earth. Because the moon's orbit is somewhat elliptical it's speed in orbit varies, but it's rotational speed is quite uniform. The change in speed causes the moon to appear to swing back and forth over the course of a month, a phenomenon called "libration". The elliptical shape of the moons orbit causes the moon to appear larger or smaller depending on its distance from the earth. The lunation depicted above is from October 2007, and happens to be a "supermoon", when perigee and full moon closely coincided.

[Lonesome in Massachussets]

The moon is "tidally locked" in its orbit around the earth. On average, it rotates at the same rate at which it orbits, so that it mostly keeps the same face towards the earth. Because the moon's orbit is somewhat elliptical it's speed in orbit varies, but it's rotational speed is quite uniform. The change in speed causes the moon to appear to swing back and forth over the course of a month, a phenomenon called "libration". The elliptical shape of the moons orbit causes the moon to appear larger or smaller depending on its distance from the earth. The lunation depicted above is from October 2007, and happens to be a "supermoon", when perigee and full moon closely coincided.