In defining a plane, you can describe it as a flat two-dimensional surface. But how could a not perfectly co-planar Milky Way have a plane? Galaxies are normally irregular in shape. In space or in a galaxy, a plane is described as where most of the galaxy’s mass lies. It is then called the galactic plane. And perpendicular to it are the galactic poles. The poles are then named north, if it is above the galactic plane and south if it is below.
Galactic planes are calculated based on 1,000 light-year thickness of stars. Astronomers, to get more detail of a galactic plane, draw a line from the sun to the galaxy’s center. From there, coordinates are measured within the galactic plane. From those measurements, you can have the longitude and the latitude.
There were issues regarding the solar system passing through the galactic plane. If you learn more about the galaxy’s elements, you should know by now that the solar system lies on a galactic plane. It really does go up or down across the plane. If there is one thing to be scared of, it is the effect of electromagnetic fields to volcanic activities, tides earthquakes, and others when the passing of the solar system to galactic plane occur.