Spiral Arms
Regions of stars and interstellar matter that extend from the center of spiral galaxies, forming a spiral pattern; in the Milky Way, these include the Orion Arm where our Solar System resides.
Source: esa.int
APODs including "Spiral Arms"
NGC 6384: Spiral Beyond the Stars
22/03/2011
The universe is filled with galaxies. But to see them astronomers must look out beyond the stars of our galaxy, the Milky Way. For example, consider this colorful telescopic view of spiral galaxy NGC 6384, about 80 million light-years away in the direction of the constellation Ophiuchus. At that distance, NGC 6384 spans an estimated 150,000 light-years, but this close-up of the galaxy's central region is about 70,000 light-years wide. The sharp image shows details in the distant galaxy's blue spiral arms and yellowish core. Still, the individual stars seen in the picture are all in the close foreground, well within our own galaxy. The brighter Milky Way stars show noticeable crosses, or diffraction spikes, caused by the telescope itself.