A megaparsec (Mpc) is a unit of measurement used in astrophysics and cosmology to express vast distances on cosmic scales. It is equal to one million parsecs. A parsec (pc) is a unit of length used in astronomy to describe astronomical distances, and it is approximately equal to 3.09 × 10^16 meters or 3.09 × 10^13 kilometers.
So, a megaparsec is equivalent to:
1 megaparsec (Mpc) = 1,000,000 parsecs (pc)
Megaparsecs are typically used to describe distances between galaxies and galaxy clusters in the universe. Since astronomical distances are extremely large, the parsec and its multiples, such as the megaparsec, provide a convenient way to express these distances without dealing with unwieldy numbers of kilometers or light-years. Cosmologists often use megaparsecs when discussing the large-scale structure of the universe, the size of galaxy clusters, and the expansion of the cosmos.
A "finger" is a traditional unit of length used for measuring cloth or fabric. Similar to the span, the finger is based on the width of a human finger. It was historically used in various countries, including England.
In England, a finger was typically equal to about 2.25 inches or approximately 5.715 centimeters. However, like other traditional units of measurement, the precise length of a finger could vary depending on the region and historical context.