Earth's equatorial radius, often denoted as "R," is the distance from the center of the Earth to the point on the Earth's surface that lies along the equator. It represents the Earth's average radius when measured from its center to its equatorial surface. The equatorial radius is greater than the polar radius because the Earth is slightly flattened at the poles and bulges at the equator due to its rotation.
The approximate value for Earth's equatorial radius is about 6,378.1 kilometers (or approximately 3,963.2 miles). This value may vary slightly depending on the reference ellipsoid used for modeling the Earth's shape, but the given value is a commonly used and accurate approximation for most purposes.
In contrast to the equatorial radius, Earth's polar radius (measured from the center to a point on the Earth's surface at the North or South Pole) is slightly shorter, approximately 6,357 kilometers (3,949 miles).
A "famn" is a historical unit of length used for measuring depth or distance in nautical and maritime contexts. The term "famn" is of Swedish origin and was widely used in Scandinavian countries and regions with maritime traditions.
The exact length of a famn could vary by region and historical period, but it was typically around 1.8 to 2.2 meters (approximately 5.9 to 7.2 feet). It was commonly used for measuring water depth when navigating, anchoring, or fishing.
Like many historical units of measurement related to nautical and maritime activities, the use of the famn has largely been replaced by modern and standardized systems, such as meters or feet, for precise measurements in navigation and marine industries. However, you may still encounter the term "famn" in historical or traditional maritime contexts.