How the Moon Changes During its Orbital Path
When the Moon, the Earth's satellite, passes from apogee to perigee, certain changes occur regarding its size, brightness and position. The distance of the Moon slightly changes as it passes from these points, making the mean distance 384,401 km. During the years 1750 and 2125, the closest perigee was at a distance of 356,375 km on 4th of January 1912, and the furthest apogee of the Moon will be 406,720 km away on the 3rd of February 2125.
Although the difference in the Moon's size cannot be directly observed, it is quite significant. The image shows the relative size difference when the Moon passes from these points.
A full Moon near perigee is a lot brighter than a full Moon near apogee. As a matter of fact, the Moon may shine 30% or 1.3 times brighter at perigee and this amount is also due to the logarithmic response of the human eye as far as light is concerned. The relative differences in brightness and size are difficult to observe because there is no absolute reference to compare them with.
Position of Features
Another significant change during apogee and perigee is a slight alteration in the position of features on the Moon disc. Although we are familiar with the concept that the Moon always shows the same side toward the Earth, we can in fact observe 59% of the Moon's surface. This is due to the eccentricity and the inclination of the Moon's orbit around the Earth. During the course of its orbit, the Moon appears to nod up, down, left and right, or rotate around Mare Crisium, the dark circle near the upper right limb of the Moon.
Click here to see an animation of how the Moon changes when it passes from these points.