Astronomy Glossary
There are currently 3 names in this directory beginning with the letter P.
P
penumbra
(a) Less than full shadow (umbra).
(b) The portion of a shadow in which light from an extended source is partially but not completely cut off by an intervening body; the area of partial shadow surrounding the umbra.
(b) The portion of a shadow in which light from an extended source is partially but not completely cut off by an intervening body; the area of partial shadow surrounding the umbra.
perigee
The point at which a body orbiting the Earth (such as the Moon or an artificial satellite) is closest to the Earth.
