Milky Way’s giant waves may have been created by another galaxy

The Milky Way appears to have giant ripples that extend across at least a quarter of its disk. If confirmed, the structure could be the remnant of a collision with another galaxy, but not all astronomers are convinced it actually exists.

In illustrations, our galaxy is commonly depicted as a flattened disk with a central bulge, but its structure is much more complex. Astronomers have mapped the rippling clouds of stars and gas that make waves in a small part of our galaxy. They have also discovered that…