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.
The "cubit" (Greek: πῆχυς, pēchys) in ancient Greece was a unit of length used in antiquity for measuring various objects, including architectural dimensions. Like many ancient units of measurement, the length of the Greek cubit could vary over time and by region.
The most commonly referenced Greek cubit is the "common" or "short" cubit, which is believed to have been approximately 45 centimeters (about 17.7 inches) in length. However, there were variations in the length of the cubit in different parts of Greece and during different periods in ancient history.
The Greek cubit was used for measuring building dimensions, as well as in various crafts and trades. It was often based on the length of the forearm from the elbow to the tip of the middle finger, much like other cubits used in different ancient cultures.
It's important to note that the length of the Greek cubit is a matter of historical interpretation and may not be precisely defined due to variations in antiquity.