Category:Astrolabe

As"tro*labe, n. Etym: [OE. astrolabie, astrilabe, OF. astrelabe, F. astrolabe, LL. astrolabium, fr. Gr.

1. (Astron.)

Defn: An instrument for observing or showing the positions of the stars. It is now disused.

Note: Among the ancients, it was essentially the armillary sphere. A graduated circle with sights, for taking altitudes at sea, was called an astrolabe in the 18th century. It is now superseded by the quadrant and sextant.

2. A stereographic projection of the sphere on the plane of a great circle, as the equator, or a meridian; a planisphere. Whewell.