The galactic coordinate system
The galactic coordinate system disregards celestial equators and celestial poles.
The center line of the Milky Way determines the galactic equator.
The galactic longitude of a star is defined as the angle between the baseline of the center of the Galaxy and
the Sun and the line between the star and the Sun.
The galactic longitude l is measured in degrees (0° to 360).
The galactic latitude b (0° to +-90°)
represents the angle between the line of sight from the Sun to the star and the galactic plane.
The Sun revolves about the Center of the Galaxy in clockwise direction given
the Galactic North Pole as a viewpoint.
The period of the sun's revolution is about 240 million years.