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The equator is divided into 360 degrees of longitude, so each degree at the equator represents 111,319.5 metres (365,221 ft). As one moves away from the equator towards a pole, however, one degree of longitude is multiplied by the cosine of the latitude, decreasing the distance, approaching zero at the pole.
Since one degree is 1 / 360 of a turn, or complete rotation, one arcminute is 1 / 21 600 of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth's circumference is very near 21 600 nmi. A minute of arc is π / 10 800 of a radian.
With this value for R the meridian length of 1 degree of latitude on the sphere is 111.2 km (69.1 statute miles) (60.0 nautical miles). The length of one minute of latitude is 1.853 km (1.151 statute miles) (1.00 nautical miles), while the length of 1 second of latitude is 30.8 m or 101 feet (see nautical mile).
= 2.54 × 10 −5 m: mil (Sweden and Norway) mil ≡ 10 km = 10 000 m: mile (geographical) (H) ≡ 6082 ft = 1 853.7936 m: mile (international) mi ≡ 80 chains ≡ 5280 ft ≡ 1760 yd: ≡ 1 609.344 m: mile (tactical or data) ≡ 6000 ft: ≡ 1 828.8 m: mile (telegraph) (H) mi ≡ 6087 ft = 1 855.3176 m: mile (US Survey) mi
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).
Degrees, minutes and seconds, when used, must each be separated by a pipe ("|"). Map datum must be WGS84 if possible (except for off-Earth bodies). Avoid excessive precision (0.0001° is <11 m, 1″ is <31 m). Maintain consistency of decimal places or minutes/seconds between latitude and longitude. Latitude (N/S) must appear before longitude (E/W).
Degrees and minutes were the usual units of angular measurement but ... which equals 3 m at 1000 m (or 0.3 m at 100 m) ... for instance a target known to be 1.5 m in ...
where φ (°) = φ / 1° is φ expressed in degrees (and similarly for β (°)). On the ellipsoid the exact distance between parallels at φ 1 and φ 2 is m(φ 1) − m(φ 2). For WGS84 an approximate expression for the distance Δm between the two parallels at ±0.5° from the circle at latitude φ is given by