Which description correctly identifies the Milky Way?

• A. A small irregular galaxy.
• B. A giant elliptical galaxy.
• C. A region outside the galaxy containing no stars.
• D. A large spiral galaxy that contains the Solar System.

Answer: (D)

Spiral galaxies are flat, rotating systems with a central bulge and spiral arms where gas, dust, and young stars are found. The Milky Way is one of these, containing a disk of stars and gas with spiral arms and a central bulge, and our Solar System sits inside one of those arms. It isn’t a small irregular galaxy, which would lack a regular shape and clear arms, nor a giant elliptical galaxy, which would be more rounded and mostly feature older stars with little gas or ongoing star formation. It also isn’t a region outside a galaxy with no stars. So the description that the Milky Way is a large spiral galaxy that contains the Solar System is the correct one.