Galactic year

The galactic year, also known as a cosmic year, is the length of time needed for the Sun to orbit once around the center of the Milky Way Galaxy.^[1] One galactic year is 230 million Earth years.^[2] The Solar System is traveling at an average speed of 230 km/s (828,000 km/h) within its arc-like path around the galactic center,^[3] a speed at which an object could travel around the Earth's equator in 2 minutes and 54 seconds; that speed goes along with about 1/1300 of the speed of light.

The orbit of the Sun (yellow circle ring) around the galactic center

The galactic year provides a conveniently usable unit for showing cosmic and geological time periods together. Very differently, a "billion-year" scale does not allow for useful difference between geologic events, and a "million-year" scale needs some rather large numbers.^[4]

Galactic Year Media

The orientation of the Solar System's motion

References

↑ Cosmic Year Archived 2014-04-12 at the Wayback Machine, Fact Guru, University of Ottawa
↑ Leong, Stacy (2002). "Period of the Sun's Orbit around the Galaxy (Cosmic Year)". The Physics Factbook.
↑ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question18.html NASA – StarChild Question of the Month for February 2000
↑ Geologic Time Scale – as 18 galactic rotations

[akb-1] Cosmic Year Archived 2014-04-12 at the Wayback Machine, Fact Guru, University of Ottawa

[biblio-2] Leong, Stacy (2002). "Period of the Sun's Orbit around the Galaxy (Cosmic Year)". The Physics Factbook.

[StarChild-3] ttp://starchild.gsfc.nasa.gov/docs/StarChild/questions/question18.html NASA – StarChild Question of the Month for February 2000

[timeline-4] Geologic Time Scale – as 18 galactic rotations

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