|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
Earth radius is the distance from Earth's center to its surface, about 6,371 km (3,959 mi). This length is also used as a unit of distance, especially in astronomy and geology, where it is usually denoted by R⊕.
A cable length or length of cable is a nautical unit of measure equal to one tenth of a nautical mile or approximately 100 fathoms. The unit is named after the length of a ship's anchor cable in the Age of Sail. The definition varies: