Gigameter
A gigameter (Gm) is a unit of length in the metric system, equal to 1 billion meters (1 Gm = 10⁹ meters). Gigameters are used to measure very large distances, often within the solar system. For example, the average distance from Earth to the Sun is about 150 gigameters, or 1 astronomical unit (AU). While not commonly used in everyday life, gigameters are helpful in astronomy and space science to describe distances between planets or other celestial bodies.
Fathom (US Survey)
The fathom (US survey) is a unit of length used in U.S. surveying and nautical contexts, defined as exactly 6 US survey feet. Since one US survey foot is approximately 0.3048006096 meters, the US survey fathom measures about 1.828804 meters.
Like the international fathom, it is primarily used to measure water depths and underwater distances in marine navigation and surveying.
Key details:
Though the difference between the US survey fathom and the international fathom is very small, the US survey units are being phased out in favor of international standards, but they still appear in some legal and historical surveying documents.
No conversions available for length.