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The nanometre ( SI symbol: nm) is a unit of length in the metric system equal to 10−9 metres ( 1 1 000 000 000 m = 0.000 000 001 m ). To help compare different orders of magnitude, this section lists lengths between 10 −9 and 10 −8 m (1 nm and 10 nm). 1 nm – diameter of a carbon nanotube.
Earth radius (denoted as R 🜨 or R E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid (an oblate ellipsoid), the radius ranges from a maximum (equatorial radius, denoted a) of nearly 6,378 km (3,963 mi) to a minimum (polar radius, denoted b) of nearly 6,357 km (3,950 mi).
Geodesy. Earth's circumference is the distance around Earth. Measured around the equator, it is 40,075.017 km (24,901.461 mi). Measured passing through the poles, the circumference is 40,007.863 km (24,859.734 mi). [ 1] Measurement of Earth's circumference has been important to navigation since ancient times. The first known scientific ...
1–10 μm — diameter of a typical bacterium. 1.55 μm — wavelength of light used in optical fibre. 3–4 μm — size of a typical yeast cell. 5 μm — length of a typical human spermatozoon 's head [ 22] 6 μm — anthrax spore. 7 μm — diameter of the nucleus of a typical eukaryotic cell.
The lunar distance is on average approximately 385,000 km (239,000 mi), or 1.28 light-seconds; this is roughly 30 times Earth's diameter or 9.5 times Earth's circumference. Around 389 lunar distances make up an AU astronomical unit (roughly the distance from Earth to the Sun). Lunar distance is commonly used to express the distance to near ...
The cubic metre (in Commonwealth English and international spelling as used by the International Bureau of Weights and Measures) or cubic meter (in American English) is the unit of volume in the International System of Units (SI). [ 1] Its symbol is m3. [ 1] It is the volume of a cube with edges one metre in length.
The standard railway track gauge, fixed at 4 feet 8 + 1 ⁄ 2 inches (1,435.1 mm) in 1845, [82] was redefined as 1,435 mm [83] – a nominal decrease of 0.1 mm but within the engineering tolerances. Motorway marker posts used by road maintenance teams and emergency services demarcate locations in multiples of 100 m. [84]
Earth's outer core is a fluid layer about 2,260 km (1,400 mi) thick, composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. [ 1][ 2][ 3] The outer core begins approximately 2,889 km (1,795 mi) beneath Earth's surface at the core-mantle boundary and ends 5,150 km (3,200 mi) beneath Earth's surface at ...