astronomical unit

plural astronomical units

1. astronomy149,597,870,700 metres, the approximate mean distance from the Earth to the Sun (the semi-major axis of Earth's orbit), (symbol AU), used to measure distances in the solar system.

   2 more examples

   Now this big quarter of a Jupiter mass planet is in an orbit about Zeta 2 Reticuli which lasts 18.9 days and has a Semi-Major Axis of 0.14 Astronomical Unit (AU). For comparison Mercury has a Semi-Major Axis of 0.387 AU equal to 36 million miles and Earth has a Semi-Major Axis of 1.00 AU equal to 92.9 million miles. Now if we assume that this newly discovered planet, which we will name Reticulum 1 in accordance with Bob Lazar’s convention, is the closest one to Zeta 2 Reticuli (it’s hard to imagine a closer one), then following Bode’s Law (the law which states each planet is about twice the distance from it’s sun as its inner neighbor) Reticulum 2 should be at 0.28 AU, Reticulum 3 should be at 0.56 AU and, INTERESTINGLY, Reticulum 4 would be at 1.12 AU in between the Earth’s 1.00 AU and Mars’s 1.52 AU, well within the “life-zone” of a G class star!

   2000 April 10, Joe LeSearne, “Zeta 2 Reticuli : Home System Of The Greys?”, in http://www.gravitywarpdrive.com/, retrieved 05 Aug 2012

   Gagarin Station is the largest deep space station built by humanity, a "Bernal Sphere" designed with a 500-meter-diameter habitable area. It was constructed beyond Pluto, nearly 80 Astronomical Units (12 billion kilometers) from Sol. Moving crew and materials to this location bankrupted most of the backers.

   2008, BioWare, Mass Effect, Redwood City: Electronic Arts, →ISBN, →OCLC, PC, scene: Stations: Gagarin Station Codex entry

   Synonyms: A.U., a.u., AU, au, ua, ㍳, a. u., A. U.