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A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. [2] [3] [4] Historically, it was defined as the meridian arc length corresponding to one minute ( 1 / 60 of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees).
From 1630 to 1718 a millia was 5,564 feet (1,696 metres), making a geographical league of four millias equal 22,256 feet (6,784 m or 3.663 modern nautical miles). But from 1718 through the 1830s the millia was defined as the equivalent of just over 5,210 feet, giving a shorter geographical league of just over 20,842 feet (6,353 m or 3.430 ...
Knots tied at a distance of 47 feet 3 inches (14.4018 m) from each other, passed through a sailor's fingers, while another sailor used a 30-second sand-glass (28-second sand-glass is the currently accepted timing) to time the operation. [9] The knot count would be reported and used in the sailing master's dead reckoning and navigation.
Lunar distance (LD), the distance from the centre of Earth to the centre of the Moon, is a unit of measure in astronomy. The lunar distance is approximately 384,400 km (238,900 mi), or 1.28 light-seconds; this is roughly 30 times Earth's diameter. A little less than 400 lunar distances make up an astronomical unit.
The value formerly used in the United States was 6,080.20 feet = 1 nautical (geographical or sea) mile." [6] [7] This deprecated value of 6,080.2 feet is equivalent to 1,853.24 m. A separate reference identifies the geographic mile as being identical to the international nautical mile of 1,852 m and slightly shorter than the British nautical ...
Lunar distance LD ≈ 384 402 km. [15] Average distance between the center of Earth and the center of the Moon. astronomical unit au. Defined as 149 597 870 700 m. [16] Approximately the distance between the Earth and Sun. light-year ly ≈ 9 460 730 472 580.8 km. The distance that light travels in a vacuum in one Julian year. [17]
The rod, perch, or pole (sometimes also lug) is a surveyor's tool [1] and unit of length of various historical definitions. In British imperial and US customary units, it is defined as 16 + 1 ⁄ 2 feet, equal to exactly 1 ⁄ 320 of a mile, or 5 + 1 ⁄ 2 yards (a quarter of a surveyor's chain), and is exactly 5.0292 meters.
One metre is exactly equivalent to 5 000 / 127 inches and to 1 250 / 1 143 yards. A simple mnemonic to assist with conversion is "three 3s": 1 metre is nearly equivalent to 3 feet 3 + 3 ⁄ 8 inches. This gives an overestimate of 0.125 mm. The ancient Egyptian cubit was about 0.5 m (surviving rods are 523–529 mm). [27]