By studying this location, Walter Baade was able to define Population I and Population II stars.
By studying this location, Walter Baade was able to define Population I and Population II stars. Baade was specifically studying the two dense star clusters at the center of this place, which is located next to Triangulum. Ernst Hartwig observed the only supernova to occur in this place, which was discovered in the 900s CE by the Persian astronomer Abd al-Rahman. Listed as number thirty-one in the Messier catalogue, it is expected to collide with the Milky Way in about 2.5 billion years. For 10 points, name this Local Group galaxy, the closest spiral galaxy to the Milky Way.
By studying this location, Walter Baade was able to define Population I and Population II stars.
Andromeda galaxy [accept Messier 31 before "thirty-one" is read]