These are category names corresponding to distances
from the center of the Earth to the center of its moon.
Distance category names are used in the output of the
lunar.distance function if its
name option is set to TRUE.
The perigee occurs at roughly \(56\) Earth radii, and
the apogee at about \(62.8\) Earth radii.
These categories are not determined according to any
common standard.
They may have different precise definitions
for their bounds in different analyses.