A light-year is a unit of distance measurement based on the travel of light energy, undisturbed in a vacuum, over the course of one Earth year. Contents[show] History and specificsEdit A light year is about 9.5 quadrillion meters long. This article is a stub relating to science. You can help our database by expanding on it. AppendicesEdit ReferencesEdit … External linkEdit Light-year article at Wikipedia, the free encyclopedia. Retrieved from "https://memory-beta.fandom.com/wiki/Light-year?oldid=594414" Categories: Memory Beta stubs (science) Astronomical measurements Distance measurements Add category Cancel Save Community content is available under CC-BY-SA unless otherwise noted.