Our understanding of galaxies is rooted in the fact that we can see so many of them. Some, such as the Andromeda and Pinwheel galaxies are fairly close, and others are more distant, but all of them give a unique view. Because of this, we can see how the various types of galaxies appear from different points of view, from face-on to edge-on and all angles in between. But there is one galaxy that’s a bit harder to map out, and that’s our own.
One of the things they discovered is that there is a belt of high metalicity within our galaxy. Like all galaxies, the Milky Way mostly contains hydrogen and helium, but there are traces of other elements throughout the galaxy. Toward the center of the galaxy, the metallicity is fairly low, but as you move outward from the center the metallicity increase, peaking at around 23,000 light-years from the center.