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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 ...
An astronomical instrument is a device for observing, measuring or recording astronomical data. They are used in the scientific field of astronomy , a natural science that studies celestial objects and the phenomena that occur in the cosmos, with the object of explaining their origin and evolution over time.
The frame of a sextant is in the shape of a sector which is approximately 1 ⁄ 6 of a circle (60°), [3] hence its name (sextāns, sextantis is the Latin word for "one sixth"). "). Both smaller and larger instruments are (or were) in use: the octant, quintant (or pentant) and the (doubly reflecting) quadrant [4] span sectors of approximately 1 ⁄ 8 of a circle (45°), 1 ⁄ 5 of a circle (72 ...
An almucantar staff is an instrument chiefly used to determine the time of sunrise and sunset, in order to find the amplitude and consequently the variations of the compass. Usually made of pear tree or boxwood, with an arch of 15° to 30°, [3] it is an example of a backstaff. This is a drawing of an almucantar staff.
In Arabic texts, the word is translated as ākhidhu al-nujūm (Arabic: آخِذُ ٱلنُّجُومْ, lit. ' star-taker ') – a direct translation of the Greek word. [6] Al-Biruni quotes and criticises medieval scientist Hamza al-Isfahani, who stated: [6] "asturlab is an Arabisation of this Persian phrase" (sitara yab, meaning "taker of the ...
Nocturnal used to determine apparent local time by viewing the Polaris and its surrounding stars. Ring dial or astronomical ring used to measure the height of a celestial body above the horizon. It could be used to find the altitude of the Sun or determine local time. It let sunlight shine through a small orifice on the rim of the instrument.
A grand orrery is one that includes the outer planets known at the time of its construction. The word planetarium has shifted meaning, and now usually refers to hemispherical theatres in which images of the night sky are projected onto an overhead surface. Orreries can range widely in size from hand-held to room-sized.
The merkhet or merjet (Ancient Egyptian: mrḫt, 'instrument of knowing' [1]) was an ancient surveying and timekeeping instrument. It involved the use of a bar with a plumb line, attached to a wooden handle. [2] It was used to track the alignment of certain stars called decans or "baktiu" in the Ancient Egyptian. When visible, the stars could ...