galactic plane

Galactic coordinate system

The galactic coordinate system is a celestial coordinate system which is centered on the Sun and is aligned with the apparent center of the Milky Way galaxy. The "equator" is aligned to the galactic plane. Similar to geographic coordinates, positions in the galactic coordinate system have latitudes and longitudes.

Definition

The International Astronomical Union (IAU) defined the galactic coordinate system in reference to the Equatorial coordinate system in 1958. The north galactic pole is defined to be at right ascension , declination (B1950), and the zero of longitude is the great semicircle that originates from this point along the line in position angle 123° with respect to the equatorial pole. The galactic longitude increases in the same direction as right ascension. Galactic latitude is positive towards the north galactic pole, the poles themselves at ±90° and the galactic equator being zero.

The equivalent system referred to as J2000 has the north galactic pole at (J2000), the zero of longitude at the position angle of 122.932°. The point in the sky at which the galactic latitude and longitude are both zero is (J2000). This is offset slightly from the radio source Sagittarius A*, which is the best physical marker of the true galactic center. Sagittarius A* is located at (J2000), or galactic longitude , galactic latitude .

Nomenclature

The symbols l and b are used to represent the galactic longitude and latitude, respectively.

See also

References

External links

Search another word or see galactic planeon Dictionary | Thesaurus |Spanish
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature