Convert Span (Cloth) (span) to Earth's Polar Radius (R⊕ (p)) instantly.
About these units
Span (Cloth) (span)
The span is a unit traditionally used in textile measurement, equal to the distance between the tip of the thumb and the tip of the little finger when the hand is fully extended, approximately 22.86 cm (9 inches). This anthropometric unit was widely used by weavers and cloth merchants to measure lengths of fabric quickly and intuitively. Its small scale made it convenient for practical applications where tape measures or rulers were unavailable. The span also appears in cultural and historical texts as a natural unit of human proportion. While largely obsolete today, it offers insight into pre-industrial textile practices and the anthropometric basis of early measurement systems.
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.