CHINESE astronomers have recently transformed our understanding of the spiral structure of the Milky Way. They determined that it is more like a common multiple-arm galaxy, rather than a special galaxy with four spiral arms extending from its inner parts to its outer parts.

Largely speaking, there are three types of spiral galaxies in the universe. Grand-design spiral galaxies are characterized by clear, long and symmetrical spiral arms. Flocculent galaxies are fragmented, consisting of many short, irregular and patchy segments.

Multiple-arm spiral galaxies are of an intermediate type. About 83% of such galaxies have an inner two-arm symmetry and several irregular arms in their outer parts. Only about 2% have four spiral arms extending to their outer regions, and astronomers previously believed that the Milky Way was of this special four-arm type.(Xinhua)