Libra
12-01-2016, 01:24 PM
Most reference books will note that because the moon rotates only once during each revolution about the Earth, we never see more than half of its total surface. The truth, however, is that we actually get to see more of it over the course of its elliptical orbit: 59 percent (almost three-fifths). ['Supermoon' Full Moons Explained]
The moon's rate of rotation is uniform but its rate of revolution is not, so we're able to see just around the edge of each limb from time to time. Put another way, the two motions do not keep perfectly in step, even though they come out together at the end of the month. We call this effect libration of longitude.
So the moon "rocks" in the east and west direction, allowing us to see farther around in longitude at each edge than we otherwise could. The remaining 41 percent can never be seen from our vantage point; and if anyone were on that region of the moon, they would never see the Earth.
The moon's rate of rotation is uniform but its rate of revolution is not, so we're able to see just around the edge of each limb from time to time. Put another way, the two motions do not keep perfectly in step, even though they come out together at the end of the month. We call this effect libration of longitude.
So the moon "rocks" in the east and west direction, allowing us to see farther around in longitude at each edge than we otherwise could. The remaining 41 percent can never be seen from our vantage point; and if anyone were on that region of the moon, they would never see the Earth.
![[-]](https://gayspeak.com/images/duende_v3_local/collapse.png)
