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Bya
 
 
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In astronomy
Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
, geology
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
, and paleontology
Paleontology

File:Geological time spiral - sharper.pngPaleontology from Greek: pa?a??? "old, ancient", ??, ??t- "being, creature", and ????? "speech, thought" is the study of prehistory life, including organisms' evolution and interactions with each other and their environments ....
, bya or "b.y.a." is an acronym for billion years ago. This abbreviation is commonly used as a unit
Units of measurement

The definition, agreement and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day....
 of time
Time

Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
 to denote length of time before the present. Specifically, one bya is equal to 109 year
Year

A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit....
s ago.

The "billion" in bya is, by convention, the short-scale billion
Long and short scales

The long and short scales are two different numerical systems used throughout the world:Note that the difference between the two scales grows as numbers get larger....
 (109) of American preference, not the long-scale billion (1012) of British usage.






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In astronomy
Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
, geology
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
, and paleontology
Paleontology

File:Geological time spiral - sharper.pngPaleontology from Greek: pa?a??? "old, ancient", ??, ??t- "being, creature", and ????? "speech, thought" is the study of prehistory life, including organisms' evolution and interactions with each other and their environments ....
, bya or "b.y.a." is an acronym for billion years ago. This abbreviation is commonly used as a unit
Units of measurement

The definition, agreement and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day....
 of time
Time

Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
 to denote length of time before the present. Specifically, one bya is equal to 109 year
Year

A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit....
s ago.

The "billion" in bya is, by convention, the short-scale billion
Long and short scales

The long and short scales are two different numerical systems used throughout the world:Note that the difference between the two scales grows as numbers get larger....
 (109) of American preference, not the long-scale billion (1012) of British usage. For this reason, there is some potential for confusion; and some scientists prefer the unit Gya
Gya

In astronomy, geology, and paleontology, Gya is often used as an Units of measurement of time to denote length of time before the present. Specifically, one Gya is equal to 109 years ago....
, while others prefer Ga (Giga annum). However, bya remains in more widespread use.

Like the related unit mya
Mya (unit)

In astronomy, geology, and paleontology, mya or "m.y.a." is an abbreviation for "million years ago". Like the related unit bya, mya is traditionally written in lower case....
 ("million years ago"), bya is traditionally written in lowercase. Ga or Gya has a capitalized
Capitalization

Capitalization is writing a word with its first grapheme as a majuscule and the remaining letters in Lower case , in those writing systems which have a letter case....
 first letter instead.

Events around 1 to 13 bya:


Astronomic
Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
 light years:

  • The Big Bang
    Big Bang

    The Big Bang is the physical cosmology model of the initial conditions and subsequent development of the universe supported by the most comprehensive and accurate explanations from current scientific method and observation....
     was 13.7 bya
  • The Milky Way
    Milky Way

    The Milky Way, sometimes called simply the Galaxy, is the galaxy in which the Solar System is located. It is a barred spiral galaxy that is part of the Local Group of galaxies....
     formed 13.6 bya
  • The Hubble Ultra Deep Field
    Hubble Ultra Deep Field

    The Hubble Ultra Deep Field, or HUDF, is an image of a small region of outer space in the constellation Fornax, composited from Hubble Space Telescope data accumulated over a period from September 24, 2003 through January 16, 2004....
     image light started >13 bya
  • The Hubble Deep Field
    Hubble Deep Field

    The Hubble Deep Field is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope....
     images light started ~12 bya
  • The sol
    Sól

    S?l may refer to:*S?l , a goddess associated with the sun in Germanic mythology*Sowilo rune*S?l, Lublin Voivodeship *S?l, Masovian Voivodeship ...
    ar system sun
    Sun

    The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
     was born 4.59 bya


Geologic
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
 Precambrian
Precambrian

The Precambrian is an informal name for the supereon comprising the eon of the geologic timescale that came before the current Phanerozoic eon....
 eon
Eon

Eon is the US English variant of the traditional aeon, which means "age" or "forever".A geologic time scale#Terminology is the second-largest division of time in geology....
s and Paleontology
Paleontology

File:Geological time spiral - sharper.pngPaleontology from Greek: pa?a??? "old, ancient", ??, ??t- "being, creature", and ????? "speech, thought" is the study of prehistory life, including organisms' evolution and interactions with each other and their environments ....
:

  • Hadean
    Hadean

    The Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources....
     4.567 to 3.80 bya
    • The Earth
      Earth

      Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
       formed 4.56717 bya (Giant impact hypothesis
      Giant impact hypothesis

      The giant impact hypothesis is the now-dominant scientific hypothesis for the formation of the Moon, which is thought to have formed as a result of a collision between the young Earth and a Mars-sized body that is sometimes called Theia ....
      )
    • Oldest known mineral
      Mineral

      A mineral is a naturally occurring solid formed through Geology processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties....
       formed 4.404 bya
    • Oldest known life form appeared around 4.0 bya
  • Archean
    Archean

    The Archean is a geology eon before the Proterozoic and Paleoproterozoic, before 2.5 Ga . Instead of being based on stratigraphy, this date is defined chronometrically....
     3.8 to 2.25 bya
    • Cyanobacteria
      Cyanobacteria

      Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis....
       possibly started photosynthesis
      Photosynthesis

      File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
       ~3.8 bya
    • Prokaryote
      Prokaryote

      The prokaryotes are a group of organisms that lack a cell nucleus , or any other cell membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus....
      s (Bacteria
      Bacteria

      The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
      ) definitely formed 3.5 bya
  • Proterozoic
    Proterozoic

    The Proterozoic is a eon representing a period before the first abundant complex life on Earth. The Proterozoic Eon extended from 2500 annum to 542.0 ? 1.0 Ma , and is the most recent part of the old, informally named ?Precambrian? time....
     2.25 to 0.5 bya
    • Eucaryotes formed 2.1 to 1.6 bya
    • First multicellular life
      Life

      Life is a characteristic of organisms that exhibit certain biological processes such as chemical reactions or other events that results in a transformation....
       started 1.2 bya
    • Neoproterozoic
      Neoproterozoic

      The Neoproterozoic Era is the unit of geologic time scale from 1,000 to 542 +/- 0.3 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods....
       Snowball Earth
      Snowball Earth

      Snowball Earth refers to hypotheses regarding paleoclimate global-scale glaciation, claiming that the Earth's surface was nearly or entirely frozen at some points in its past....
       was 0.6 bya


  • Supercontinent
    Supercontinent

    In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and terrane that form Eurasia qualifies as a supercontinent today....
    s:
    • Vaalbara
      Vaalbara

      Vaalbara is the Earth's theorized first supercontinent. According to Radiometric dating data of the encompassing cratons that constituted Vaalbara, it is believed to have existed 3.3 billion years ago and possibly as far back as 3.6 Ga....
       formed 3.6 bya
    • Ur
      Ur (continent)

      Ur is the first known continent that probably formed 3 billion years ago in the early Archean Eon . Ur joined with the continents Nena and Atlantica about one billion years ago to form the supercontinent Rodinia....
       formed ~3.0 bya
    • Kenorland
      Kenorland

      Kenorland was one of the earliest supercontinents on Earth. It is believed to have formed during the Archaean Era ~2.7 billion years ago by the accretion of Neoarchaean cratons and the formation of new continental crust....
       formed 2.6-2.0 bya
    • Hudsonia
      Columbia (supercontinent)

      Columbia is the name of one of the Earth's oldest supercontinents. It was first proposed by J.J.W. Rogers and M. Santosh, and is thought to have existed approximately 1.8 to 1.5 billion years ago in the Paleoproterozoic era , making it the oldest hypothesized continent....
       formed 1.8-1.4 bya
    • Rodinia
      Rodinia

      In geology, Rodinia is the name of a supercontinent, a continent which contained most or all of Earth's landmass. According to plate tectonic reconstructions, Rodinia existed between 1100 and 750 million years ago, in the Neoproterozoic era ....
       formed ~1 Bya and broke up ~0.75 bya
    • Pannotia
      Pannotia

      Pannotia, first described by Ian W. D. Dalziel in 1997, is a hypothetical supercontinent that existed from the Pan-African orogeny about 600 million years ago to the end of the Precambrian about 540 million years ago....
       formed ~0.5 bya
    • Pangaea
      Pangaea

      Pangaea, Pang?a or Pangea was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
       formed ~0.25 bya


See also

  • Myr
    MYR

    MYR can mean multiple things:* Malaysian ringgit, the ISO 4217 code for the currency of Malaysia* Myrtle Beach International Airport, the IATA airport code for the airport in Myrtle Beach, South Carolina...
  • annum
    Annum

    Annum is one form of the Latin noun meaning year, not a form normally used for derivatives in modern languages: the accusative case Grammatical number of the second declension grammatical gender noun annus , anni ....
  • Before Present
    Before Present

    Before Present years are a time scale used in archaeology, geology, and other science disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use 1950 Common_Era as the arbitrary origin of the age scale....
  • Gigaannum
    Annum

    Annum is one form of the Latin noun meaning year, not a form normally used for derivatives in modern languages: the accusative case Grammatical number of the second declension grammatical gender noun annus , anni ....
     or Ga
  • Gya
    Gya

    In astronomy, geology, and paleontology, Gya is often used as an Units of measurement of time to denote length of time before the present. Specifically, one Gya is equal to 109 years ago....
  • mya (unit)
    Mya (unit)

    In astronomy, geology, and paleontology, mya or "m.y.a." is an abbreviation for "million years ago". Like the related unit bya, mya is traditionally written in lower case....
  • Orders of magnitude (time)#Years
    Orders of magnitude (time)

    Seconds...