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Galactic year

 

 
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Galactic year
 
 
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The galactic year, also known as a cosmic year, is the duration of time required for the solar system
Solar System

The Solar System consists of the Sun and those Astronomical object bound to it by gravity: the eight planets and five dwarf planets, their 173 known Natural satellite, and billions of Small Solar System body....
 to orbit
ORBit

ORBit is a Common Object Request Broker Architecture 2.4 compliant Object Request Broker . It features mature C , C++ and Python bindings, and less developed bindings for Perl, Lisp , Pascal , Ruby , and Tcl....
 once around the center of the Milky Way galaxy. Estimates of the length of one orbit range from 225 to 250 million "terrestrial" 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.

The galactic year provides a conveniently "graspable" unit for thinking about cosmic and geological time periods. (By contrast, a "billion-year" scale does not allow for useful discrimination between geologic events, and a "million-year" scale requires some rather large numbers.)







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The galactic year, also known as a cosmic year, is the duration of time required for the solar system
Solar System

The Solar System consists of the Sun and those Astronomical object bound to it by gravity: the eight planets and five dwarf planets, their 173 known Natural satellite, and billions of Small Solar System body....
 to orbit
ORBit

ORBit is a Common Object Request Broker Architecture 2.4 compliant Object Request Broker . It features mature C , C++ and Python bindings, and less developed bindings for Perl, Lisp , Pascal , Ruby , and Tcl....
 once around the center of the Milky Way galaxy. Estimates of the length of one orbit range from 225 to 250 million "terrestrial" 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.

The galactic year provides a conveniently "graspable" unit for thinking about cosmic and geological time periods. (By contrast, a "billion-year" scale does not allow for useful discrimination between geologic events, and a "million-year" scale requires some rather large numbers.)

Timeline of earth's history in galactic years

In this list, 1 galactic year (GY) = 225 million years
  • 0 GY: Birth of the 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....
  • 4 GY: Oceans appear on 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...
  • 5 GY: 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....
     begins
  • 6 GY: Prokaryotes appear
  • 7 GY: 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....
     appear
  • 10 GY: Stable continents appear
  • 13 GY: Eukaryotes appear
  • 16 GY: Multicellular organisms appear
  • 17.8 GY: Cambrian explosion
    Cambrian explosion

    The Cambrian explosion or Cambrian radiation was the seemingly rapid appearance of most major groups of complex animals around , as evidenced by the fossil record....
  • 19 GY: Great Dying
  • 19.6 GY: K–T extinction event
  • 19.999 GY: Appearance of modern humans
    Human

    A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
  • 20 GY: Present day
    Present day

    The term "present day" is used to describe the rough period of time that surrounds the Present . Depending on the context, this period may be as narrow as referring to the immediate moment, or as broad as referring to the current year or decade....


See also

  • List of unusual units of measurement