Exameter
An exameter (Em) is a very large unit of length in the metric system. It equals one quintillion meters (1 exameter = 10¹⁸ meters). Exameters are used mainly in astronomy and physics to describe enormous distances, such as those between galaxies or across the universe. Because this unit is so huge, it’s not used for everyday measurements. The exameter helps scientists talk about the vast scale of space in a simpler way.
Rod (US Survey)
The US survey rod is a unit of length used in U.S. land surveying. It is defined as exactly 16.5 US survey feet, which is slightly longer than the international foot. Since one US survey foot equals approximately 0.3048006096 meters, the US survey rod measures about 5.0292 meters.
The survey rod, also called a pole or perch, is historically significant in the U.S. Public Land Survey System and is used to measure land boundaries and distances.
Key facts:
1 US survey rod = 16.5 US survey feet
1 US survey rod ≈ 5.0292 meters
4 US survey rods = 1 US survey chain
40 US survey rods = 1 US survey furlong
Though the US survey foot and related units are being phased out in favor of international units, the US survey rod still appears in legal land descriptions and older surveying documents.