Astronomers Find the Edge of the Milky Way’s Star-Forming Disc

Where exactly is the edge of the Milky Way? That question is harder to answer than one might expect. Since we’re inside of the galaxy itself, it’s obviously hard to judge the “edge” to begin with. But it gets even more complicated when defining what the edge even is - the galaxy simply gets less dense the farther away from the center it goes. A new paper by researchers originally at the University of Malta thinks they have an answer though. The “edge” can be defined as the star-forming region, and in their paper, published in Astronomy & Astrophysics, they very clearly show that “edge” to be between 11.28 and 12.15 kiloparsecs (or about 40,000 light years) from the center.