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 and M66
15/06/2012
Nearby and bright, spiral galaxies M65 (top) and M66 stand out in this engaging cosmic snapshot. The pair are just 35 million light-years distant and around 100,000 light-years across, about the size of our own spiral Milky Way. While both exhibit prominent dust lanes sweeping along their broad spiral arms, M66 in particular is a striking contrast in red and blue hues; the telltale pinkish glow of hydrogen gas in star forming regions and young blue star clusters. M65 and M66 make up two thirds of the well-known Leo Triplet of galaxies with warps and tidal tails that offer evidence of the group's past close encounters. The larger M66 has been host to four supernovae discovered since 1973.