Convert Roman Actus (actus) to Petameter (Pm) instantly.
About these units
Roman Actus (actus)
The Roman actus was an ancient Roman unit of length measuring 120 Roman feet, or about 35.5 meters. It played an essential role in Roman land surveying and agriculture, forming part of the system used to organize farms, roads, and territorial divisions in the expanding Roman world. The actus helped define a square unit of land known as the actus quadratus, which was used for taxation, distribution of land to soldiers, and standardizing plots throughout Roman colonies. Surveyors relied on tools like the groma to lay out straight lines based on actus subdivisions, giving Roman lands their characteristic grid patterns. Although long obsolete, the actus provides key insights into Roman engineering, colonial administration, and agricultural policy. Many European land patterns can trace their roots back to Roman measurement practices — a testament to the enduring legacy of Roman surveying.
Petameter (Pm)
A petameter is 10¹⁵ meters and begins bridging the gap between solar system scales and the nearest stars. Distances between stars, the size of large cosmic structures, or the wavelengths of extremely low-frequency electromagnetic waves may be expressed in petameters. For example, a light-year is about 9.46 petameters. Petameters rarely appear in everyday astronomical writing because traditional units like light years and parsecs are more intuitive to astronomers and the public. However, the unit's alignment with SI conventions makes it essential in scientific computation and large-scale modeling, especially when dealing with cosmic distances while maintaining strictly metric consistency.