Halley's Comet or Comet Halley (officially designated 1P/Halley) is the most famous of the periodic comets and can currently be seen every 75–76 years. Many comets with long orbital periods may appear brighter and more spectacular, but Halley is the only short-period comet that is clearly visible to the naked eye, and thus, the only naked-eye comet certain to return within a human lifetime. During its returns to the inner solar system, it has been observed by astronomers since at least 240 BC, but it was not recognized as a periodic comet until the eighteenth century when its orbit was computed by Edmond Halley, after whom the comet is now named. Halley's Comet last appeared in the inner Solar System in 1986, and will next appear in mid-2061.