Galactic Equator

The galactic equator (or galactic plane) is an imaginary plane that slices the Galaxy in half (top and bottom). In the galactic coordinate system, the equator is at galactic latitude b = 0.

Galactic coordinate system. Positions of objects are measured in terms of their galactic longitude( l ) and galactic latitude ( b ). The galactic equator slices the Galaxy in half (top and bottom).

The galactic equator is tilted at an angle of 63 degrees to the celestial equator. Since the ecliptic, the path of the Sun on the sky, is inclined at an angle of 23.5 degrees to the celestial equator, the galactic equator and ecliptic are nearly at right angles (63 + 23.5 = 86.5 degrees), although this is purely coincidental.

A line passing through the observer perpendicular to the galactic equator passes through the north galactic pole (NGP) and south galactic pole on the celestial sphere.

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