Bya: Difference between revisions
Bear-rings (talk | contribs) |
Bear-rings (talk | contribs) [Europe]]an |
||
| Line 4: | Line 4: | ||
In [[astronomy]], [[geology]], and [[paleontology]], "'''bya'''" or "'''b.y.a.'''" is an [[initialism]] for "'''[[1000000000 (number)|billion]] years ago'''". This abbreviation is commonly used as a [[unit of time]] to denote length of time before the present in billions of years. |
In [[astronomy]], [[geology]], and [[paleontology]], "'''bya'''" or "'''b.y.a.'''" is an [[initialism]] for "'''[[1000000000 (number)|billion]] years ago'''". This abbreviation is commonly used as a [[unit of time]] to denote length of time before the present in billions of years. |
||
The "billion" in bya is, by convention, the 10<SUP>9</SUP> "billion" of the [[Long and short scales|short scale]] of the [[United States|U.S.]]{{cn|date=April 2016}}, not the long-scale 10<SUP>12</SUP> "billion" of some [[Europe |
The "billion" in bya is, by convention, the 10<SUP>9</SUP> "billion" of the [[Long and short scales|short scale]] of the [[United States|U.S.]]{{cn|date=April 2016}}, not the long-scale 10<SUP>12</SUP> "billion" of some [[Europe]]an usage. For this reason, there is potential for some confusion; and some scientists prefer the unit [[Gya]], while others prefer [[Giga-annum|Ga]] (Giga-annum), however bya remains in more widespread use{{cn|dateyshshsbshbbs is a great =April 2016|date=May 2016}}. In 1974, the UK switched from the long scale to the short scale{{cn|date=April 2016}}. |
||
Related units are [[Mya (unit)|mya]] ("million years ago"), and '''byr''' ("billion years"). These are traditionally written in [[lowercase]]. [[Giga-annum|Ga]] or Gya has a [[capitalization|capitalized]] first letter instead. |
Related units are [[Mya (unit)|mya]] ("million years ago"), and '''byr''' ("billion years"). These are traditionally written in [[lowercase]]. [[Giga-annum|Ga]] or Gya has a [[capitalization|capitalized]] first letter instead. |
||
Revision as of 16:28, 18 January 2017
 |
In astronomy, geology, and paleontology, "bya" or "b.y.a." is an initialism for "billion years ago". This abbreviation is commonly used as a unit of time to denote length of time before the present in billions of years.
The "billion" in bya is, by convention, the 109 "billion" of the short scale of the U.S.[citation needed], not the long-scale 1012 "billion" of some European usage. For this reason, there is potential for some confusion; and some scientists prefer the unit Gya, while others prefer Ga (Giga-annum), however bya remains in more widespread use[citation needed]. In 1974, the UK switched from the long scale to the short scale[citation needed].
Related units are mya ("million years ago"), and byr ("billion years"). These are traditionally written in lowercase. Ga or Gya has a capitalized first letter instead.