Byr 1559376 218979411 2008-06-13T01:10:19Z Kevin Murray 1032142 no consensus to merge '''Byr''' was formerly used in [[English-language]] [[geology]] and [[astronomy]] as a [[physical unit|unit]] of one [[1,000,000,000 (number)|billion]] [[year]]s. The "B" is an abbreviation for "billion" (meaning thousand million), with "yr" simply an abbreviation for "year". Today, the term [[gigaannum]] (Ga) is also used, but Gy or Gyr are still sometimes used in English-language works (at the risk of confusion with the [[gray (unit)|gray]]). Because a [[Long and short scales|billion]] means 1000 million in some countries but can mean a million million in others its use is deprecated in favour of [[giga-]] which unambiguously means 10<sup>9</sup> and [[annum]] which for precision may be qualified by ([[sidereal]]), ([[Julian calendar|Julian]]), etc. ==See also== *[[gigaannum]] *[[Myr]] [[Category:Units of time]] {{standard-stub}}