Gigameter (Gm): A gigameter is equal to one billion (10^9) meters. It is used for long-distance measurements, such as the size of celestial objects or interplanetary distances.
A "span" is a traditional unit of length used for measuring cloth or fabric. It was historically used in various countries, including England, and is based on the width of the human hand or the spread of the fingers. The actual length of a span could vary depending on the region and historical context.
In England, a span was typically equal to 9 inches or approximately 22.86 centimeters. However, it's important to note that the definition of a span could vary from place to place and over time.