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When the astrolabe is held vertically, the alidade can be rotated and the sun or a star sighted along its length, so that its altitude in degrees can be read ("taken") from the graduated edge of the astrolabe; hence the word's Greek roots: "astron" (ἄστρον) = star + "lab-" (λαβ-) = to take.
An astrolabe from the Mughal era exhibited at the National Museum in New Delhi, India. Yantrarāja is the Sanskrit name for the ancient astronomical instrument called astrolabe . It is also the title of a Sanskrit treatise on the construction and working of the astrolabe composed by a Jain astronomer Mahendra Sūri in around 1370 CE.
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a ...
Jost Bürgi and Antonius Eisenhoit: Armillary sphere with astronomical clock, made in 1585 in Kassel, now at Nordiska Museet in Stockholm. An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (on the celestial sphere), consisting of a spherical framework of rings, centered on Earth or the Sun, that represent lines of celestial ...
An astrolabe (as the word is used from the medieval period through today) is the name of a specific astronomical instrument. Another meaning are a type of Babylonian cuneiform tablets that discuss astronomy .
The astrolabe, an instrument that has its origins in Hellenistic astronomy, is a predecessor of the modern planisphere. The term planisphere contrasts with armillary sphere, where the celestial sphere is represented by a three-dimensional framework of rings.
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
The roots of the equatorium lie in the astrolabe.The history of the astrolabe dates back to roughly 220 BC in the works of Hipparchus. [6] The difference between the two instruments is that the astrolabe measures the time and position of the sun and stars at a specific location in time. [7]