Galactic year

From Simple English Wikipedia, the free encyclopedia

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]

References[change | change source]

  1. Cosmic Year Archived 2014-04-12 at the Wayback Machine, Fact Guru, University of Ottawa
  2. Leong, Stacy (2002). "Period of the Sun's Orbit around the Galaxy (Cosmic Year)". The Physics Factbook.
  3. NASA – StarChild Question of the Month for February 2000
  4. Geologic Time Scale – as 18 galactic rotations