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  2. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    Principles. The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [5] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...

  3. Million years ago - Wikipedia

    en.wikipedia.org/wiki/Million_years_ago

    Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to 1,000,000 years (i.e. 1 × 106 years), or approximately 31.6 teraseconds.

  4. Early Earth - Wikipedia

    en.wikipedia.org/wiki/Early_Earth

    According to evidence from radiometric dating and other sources, Earth formed about 4.54 billion years ago. [7] [8] [9] The current dominant theory of planet formation suggests that planets such as Earth form in about 50 to 100 million years but more recently proposed alternative processes and timescales have stimulated ongoing debate in the planetary science community. [10]

  5. Pliocene - Wikipedia

    en.wikipedia.org/wiki/Pliocene

    The Pliocene (/ ˈplaɪ.əsiːn, ˈplaɪ.oʊ -/ PLY-ə-seen, PLY-oh-; [ 6 ][ 7 ] also Pleiocene) [ 8 ] is the epoch in the geologic time scale that extends from 5.333 million to 2.58 [ 9 ] million years ago. It is the second and most recent epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed ...

  6. Age of Earth - Wikipedia

    en.wikipedia.org/wiki/Age_of_Earth

    The age of Earth is estimated to be 4.54 ± 0.05 billion years (4.54 × 109 years ± 1%).[1][2][3][4] This age may represent the age of Earth 's accretion, or core formation, or of the material from which Earth formed. [2] This dating is based on evidence from radiometric age-dating of meteorite [5] material and is consistent with the ...

  7. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    10 6: 2.5 × 10 6 ly: The Andromeda Galaxy is approximately 2.5 million light-years away. 3 × 10 6 ly: The Triangulum Galaxy , at about 3 million light-years away, is the most distant object visible to the naked eye. 5.9 × 10 7 ly: The nearest large galaxy cluster, the Virgo Cluster, is about 59 million light-years away. 1.5 × 10 8 – 2.5 ...

  8. Orders of magnitude (time) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(time)

    2.6 × 10 11 Qs (8.2 × 10 33 years): The smallest possible value for proton half-life consistent with experiment [19] 10 23 Qs ( 3.2 × 10 45 years ): The largest possible value for the proton half-life , assuming that the Big Bang was inflationary and that the same process that made baryons predominate over antibaryons in the early Universe ...

  9. Age of the universe - Wikipedia

    en.wikipedia.org/wiki/Age_of_the_universe

    In physical cosmology, the age of the universe is the time elapsed since the Big Bang.Astronomers have derived two different measurements of the age of the universe: [1] a measurement based on direct observations of an early state of the universe, which indicate an age of 13.787 ± 0.020 billion years as interpreted with the Lambda-CDM concordance model as of 2021; [2] and a measurement based ...