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"
Dusty Spiral M66
02/09/2006
When morning twilight came to the Paranal Observatory in Chile, astronomers Mark Neeser and Peter Barthel interrupted their search for faint quasars, billions of light-years away. And just for a moment, they used Very Large Telescopes at the European Southern Observatory to appreciate the beauty of the nearby Universe. One result was this stunning view of beautiful spiral galaxy M66, a mere 35 million light-years away. About 100 thousand light-years across with striking dust lanes and bright star clusters along sweeping spiral arms, M66 is well known to astronomers as a member of the Leo Triplet of galaxies. Gravitational interactions with its neighborhood galaxies have likely influenced the shape of dusty spiral M66.