Convert Earth's Polar Radius (R⊕ (p)) to Nautical Mile (UK) (NM (UK)) instantly.
About these units
Earth's Polar Radius (R⊕ (p))
The Earth's polar radius is approximately 6,356.8 km, slightly shorter than the equatorial radius due to the Earth's flattening at the poles. This measurement is critical in modeling Earth's shape, gravity field, and rotation. It impacts satellite orbits, geodetic surveys, and global positioning systems (GPS). The difference between the equatorial and polar radii also explains phenomena such as centrifugal force variations, equatorial bulges, and sea level differences across latitudes. Understanding R⊕ (p) is essential for precision navigation, Earth science, and astronomy.
Nautical Mile (UK) (NM (UK))
The UK nautical mile was historically defined as 6,080 feet, slightly longer than the international nautical mile (1,852 meters). Before international standardization in 1929, British charts and maritime documents relied on this definition. It approximated one minute of latitude but used British feet rather than an exact metric conversion. Although the UK adopted the international nautical mile long ago, many older navigation charts, historical records, and maritime traditions still reference the UK version. Researchers dealing with archival naval documents must carefully distinguish between the two definitions to avoid errors in distance or speed calculations. The UK nautical mile is a reminder of the era before global standardization when each nation maintained its own measurement conventions—even for activities as universally critical as seafaring.