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The band of light that we call the Milky Way is actually the plane of the disk of our spiral galaxy (see this representation). It contains approximately 200 billion stars, mostly grouped into a flattened disk with a bulge at its centre.
The adjacent diagram shows schematically from top and side views what we believe to be the dimensions of our galaxy. The visible matter of the galaxy is approximately 30 kpc across (almost 100,000 light years), with the Sun in the disk about 8.5 kpc from the center. The disk is comparatively thin, only about 1000-2000 light years thick, with the dense dust-containing portion less than half that thickness. The halo of globular clusters also has a diameter at least comparable to the 30 kpc diameter of the disk.