What galactic latitude marks the Milky Way's midplane?

The Milky Way’s midplane is marked by a galactic latitude of 0 degrees. In the galactic coordinate system, latitude measures how far an object lies north or south of the galactic equator, the coordinate system’s reference plane.

The value works much like 0° latitude on Earth’s equator. Positive galactic latitudes point toward the north galactic pole, while negative values point toward the south galactic pole; the poles themselves are at +90° and −90°.

A common mix-up is confusing latitude with galactic longitude. Longitude identifies a direction around the Milky Way, with 0° aimed toward the Galactic Center. Latitude instead describes vertical position relative to the galaxy’s broad disk.

The coordinate system is centered on the Sun, not on the Milky Way’s physical center. Consequently, the defined galactic plane is a useful observational reference plane, and the Sun’s slight offset from the true disk midplane can matter in detailed astronomical work.