Caption: "Lunar perigee and apogee apparent size comparison (from 2007 April and October 2007, when events occurred near full-phases)." (Slightly edited.)

Features:

1. The eccentricity of the Moon's orbit is 0.0549 or 5.49 %.

2. This means the Earth-Moon distance varies up and down from the mean Earth-Moon distance by about 5.5 %. The total range of variation is 11 %.

   The 11 % variation in DISTANCE causes Moon's angular diameter to vary by 11 % too.

   Note that angular diameter is always an "apparent" quantity. In astro-jargon, "apparent" means as seen from a particular vantage point which is understood to be Earth, unless otherwise stated.

3. The variation in angular diameter is probably too small ever to be noticed by casual observation since we usually see the Moon at perigee and apogee without a convenient sufficiently accurate natural STANDARD OF COMPARISON.

   But difference in angular diameter of the Moon is striking if you directly compare the angular diameters at perigee and apogee with the correct relative apparent size as in the image.

4. On the sky, the difference in the angular diameters is just a bit too small to be seen by the unaided naked eye. However, it is easily measured with simple instruments.

5. Note that the images at perigee and apogee both show full moons. In fact, only occasionally does either apsis (pl. apsides) coincide with a full moon. To explicate: the mean anomalistic month = 27.554549878 days (J2000) is the mean period between like apsides, but mean lunar month = 29.530588861 days (J2000). So there is a fairly long interval before an apsis and full moon cycle back into concidence after a given coincidence.

   Astronomical perturbations account for the fact that the mean anomalistic month = 27.554549878 days (J2000) and the mean lunar sidereal month 27.321661547 days (J2000) ≅ 27.32166 days (to 7 digits) ≅ 27.3 days (the true orbital period relative to the observable universe) are NOT the same.

6. By the by, a supermoon is a near-perigee occurrence of a full moon or new moon---but "supermoon" is just phony modern made-up term.