Convert Furlong (US Survey) (fur (US)) to Astronomical Unit (AU) instantly.
About these units
Furlong (US Survey) (fur (US))
The US Survey Furlong is defined as 660 US Survey Feet (~201.168 meters), exactly 10 US survey chains. It was historically used in land measurement, agriculture, and railroads. Furlongs remain relevant for interpreting historical property layouts and land grants, particularly in rural and agricultural contexts. The unit's convenience derives from its direct relationship with the acre and chain, facilitating rapid calculation of large land areas. While the furlong is largely obsolete in modern measurement, it persists in legal and historical survey references, bridging imperial traditions and contemporary land-use documentation.
Astronomical Unit (AU)
The astronomical unit (AU) is one of the most important distance units in astronomy and planetary science. Defined as exactly 149,597,870,700 meters, it represents the average distance between Earth and the Sun. Early astronomers could estimate the AU only indirectly through geometric and observational methods; modern techniques such as radar ranging and spacecraft telemetry have vastly improved its precision. The AU serves as a natural and intuitive scale for describing distances within the solar system. Planetary orbits, asteroid trajectories, comet paths, and interplanetary mission distances are often expressed in astronomical units because they avoid cumbersome scientific notation. For instance, Jupiter orbits at about 5.2 AU from the Sun, while the asteroid belt lies roughly between 2 and 3.3 AU. Beyond practical measurement, the AU forms part of a conceptual framework for understanding solar system layout. It appears in discussions of habitable zones, solar radiation intensity, and celestial mechanics. The unit's significance extends from education to high-level astrophysics, making it one of astronomy's cornerstone measurements.