Galactic Coordinate System

The galactic coordinate system is based on spherical coordinates centered at the Sun and oriented towards the galactic center. The whole of the galaxy serves as a reference plane with Coma Berenices as the north galactic pole. A different system, the ecliptic coordinate system, uses the solar system as the reference plane and Draco as the north ecliptic pole. The axial tilt of the solar system to the galaxy is about 30°. In contrast, the axial tilt of the Earth compared to the solar system is about 23.4°.
The galactic longitude () signifies the eastward angle along the galactic plane, measured from the galactic center. It runs from 0 to radians (or 0° to 360°).
The galactic latitude () is the northward angle perpendicular to the galactic plane, measured from the galactic center. This runs from to rad (or -90° to 90°).
The distance from the Sun in kpc is denoted (). The distance to the galactic center is approximately 8 kpc. Our galactic disc is around 30 kpc wide and 1 kpc thick at the Sun's distance. It contains a central bulge with a diameter of approximately 5 kpc.


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