Definition

1. Noun:
   • An early astronomical instrument: An astrolabe is a historical device used for solving problems relating to time and the position of celestial bodies (the Sun and stars). It was a vital tool for astronomers, navigators, and astrologers for centuries.
   • A form of analog calculator: It functioned as a model of the sky, allowing users to perform calculations such as telling the time during the day or night, predicting sunrise and sunset, and determining the positions of stars.

Usage Examples

• Noun:
  • The ancient mariner used an astrolabe to navigate by the stars.
  • Museums often display beautifully crafted brass astrolabes from the Islamic Golden Age.
  • Before the invention of more precise instruments, the astrolabe was essential for astronomical observations.

Advanced Usage

• "To take a sight with an astrolabe": This phrase describes the action of using the instrument to measure the altitude of a celestial body above the horizon.
  • The explorer took a sight with his astrolabe to determine his ship's latitude.

Variants and Related Words

• Mariner's astrolabe (n): A specific, simplified type of astrolabe used primarily for navigation at sea. It was often heavier and more robust than its astronomical counterpart.
  • The mariner's astrolabe was crucial for the Age of Discovery.

Synonyms

• Analog computer (in a historical, astronomical context).
• Astronomical instrument.

Related Phrases and Concepts

• Planispheric astrolabe: The most common type, featuring a stereographic projection of the celestial sphere onto a plane.
  • The planispheric astrolabe could represent the night sky for any given time and date.

Noun

1. an early form of sextant