Umbra -
The umbra (Latin for "shadow") is the innermost and darkest part of a shadow,
where the light source is completely blocked by the occluding body.
where the light source is completely blocked by the occluding body.
Gibbous -
Having the observable illuminated part greater than a semicircle and less
than a circle.
than a circle.
Crescent -
The curved sickle shape of the waxing or waning moon.
Waxing -
Have a progressively larger part of its visible surface illuminated, increasing
its apparent size.
its apparent size.
Waning -
Have a progressively smaller part of its visible surface illuminated, so that it
appears to decrease in size.
appears to decrease in size.
Phase -
A distinct period or stage in a process of change or forming part of somethings
development.
development.