Link (US Survey)
The US survey link is a unit of length used in the United States for land surveying, defined as exactly 7.92 US survey inches. Since one US survey inch is slightly longer than the international inch (due to the US survey foot), the US survey link is approximately 0.201168 meters.
It is part of the US survey system, derived from Gunter’s chain, which is divided into 100 links per chain (66 US survey feet). Links are used to measure small distances in surveying and land measurement.
Key facts:
1 US survey link = 7.92 US survey inches
1 US survey link ≈ 0.201168 meters
100 links = 1 US survey chain (66 US survey feet)
25 links = 1 US survey rod (16.5 US survey feet)
Though the US survey units are being phased out, the US survey link still appears in historical land records and legal surveying documents.
Parsec
A parsec (pc) is a unit of distance used in astronomy, equal to about 3.26 light-years or roughly 31 trillion kilometers. The name “parsec” comes from “parallax of one arcsecond,” referring to the method astronomers use to measure distances to nearby stars based on their apparent shift when viewed from different positions in Earth’s orbit. Parsecs are commonly used to measure distances to stars and galaxies. For example, the nearest star system, Alpha Centauri, is about 1.3 parsecs away. The symbol for parsec is "pc". It’s a convenient unit for expressing large astronomical distances beyond the reach of light-years.