For the purposes of recording, cataloging, and discussing comets, there is now a standard method of nomenclature. When a comet is discovered, it is designated by the order of its discovery in that year; thus Comet 1961e was the fifth to be discovered in 1961. When its orbit has been calculated, a Roman numeral is substituted for the letter, denoting the order of the comet according to its distance from the Sun at its closest approach to the Sun (the perihelion distance). Comet 1950v was the fifth closest to the Sun in that year. Comets are usually also named after their discoverer – Comet 1961e is known as Comet Humason or Humason’s comet.