limb لبه labé (#) Fr.: bord The outer edge or border of the apparent disk of a celestial body.
→ limb brightening, → limb darkening.
The raised edge of the mater of a → planispheric astrolabe,
bearing a scale divided into
360°. The limb is the reference against which the rete is rotated in the
computation process so that the planispheric astrolabe will simulate the
sky’s appearance on a given day at a specific hour. Vice versa, the limb
can be configured from the observation of the altitude of an celestial
body on the horizon. In that case, the limb will indicate an angle that,
thanks to the hour scale on the back, can be converted into the hour of
day or night (online museo galileo, VirtualMuseum).
Etymology (EN): From L. limbus “border, hem, fringe, edge,” cognate with Skt. lambate
“hangs down.” Etymology (PE): Labé “limb, edge,” from lab “lip;” Mid.Pers. lap; cognate with
L. labium, E. lip; Ger. Lefze. |
