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"
M65 Without Moth
07/08/1998
Messier 65 (M65) is a bright spiral galaxy of stars only 35 million light-years away in the constellation Leo. With very tightly wound spiral arms, a large central bulge, and well defined dust lanes, this galaxy is a member of a group of galaxies known as the Leo triplet. The faint blue smudges along the spiral arms of M65 are large clusters of bright, newly formed stars within the distant galaxy while the bright individual stars are foreground objects in our own Milky Way galaxy. North is to the left in this composite of digital pictures taken using the large 4-meter (diameter) Mayall telescope at Kitt Peak National Observatory in the southwestern United States. The horizontal stripes are digital blemishes ... but the image has been adjusted to remove the blotch created by a moth which worked its way into the camera's filter wheel.