Byr
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Lua error in package.lua at line 80: module 'strict' not found. A gigaannum or gigayear (Byr, Gyr or Gy) is a period of one billion years (109 or 1,000,000,000 years). Retrospect time periods may be expressed as X billion years ago (bya). The prefix giga- is preferred to billion- to avoid confusion in the long and short scales over the meaning of billion; the postfix annum may be further qualified for precision as a sidereal year or Julian year.
Byr was formerly used in English-language geology and astronomy as a unit of one billion years. Subsequently the term gigaannum (Ga) has increased in usage, with Gy or Gyr still sometimes used in English-language works, at the risk of confusion with the gray). Astronomers use Gyr or Gy as an abbreviation for gigayear.[1]
See also
- Myr
- Year
- Before Present
- Gigaannum or Ga
- Gya
- mya (unit)
- Orders of magnitude (time)#Years
- Symbols y and yr
Notes
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