An astrolabe is an ancient instrument used for estimating the altitude and predicting the position of celestial objects, such as the moon, other planets, and stars.
The ancient Greeks created most of the fields of study that exist today, and along the way they created many clever devices. One was the astrolabe. An astrolabe had the same purpose as the sextant, which came later: to make astronomical measurements. An astrolabe was portable, and it consisted of a metal disc, a sighting arm, and several rotating parts used in estimating unfathomable distances. The astrolabe was an important invention in the history of astronomy and astrology.