Convert Long Reed (long reed) to Petameter (Pm) instantly.
About these units
Long Reed (long reed)
The long reed is a traditional unit of length used in Egypt and other ancient cultures, roughly equivalent to 2 cubits. It was employed in surveying, architecture, and the measurement of agricultural fields. The unit's length made it suitable for laying out longer distances with relatively few measurements, especially in river valley contexts where precision at large scales was important for irrigation and crop management. Historical records show the long reed in use for temple construction, pyramidal measurements, and land division, illustrating the practical integration of human-based units into early engineering practices.
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.