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"
M83: A Barred Spiral Galaxy
25/05/1998
M83 is a bright spiral galaxy that can be found with a small telescope in the constellation of Hydra. M83 is a member of the Centaurus group of galaxies, a nearby group dominated by the massive galaxy Centaurus A. It takes light about 15 million years to reach us from M83. The spiral arms are given a blue color by the many bright young stars that have recently formed there. Dark dust lanes are also visible. Stars and gas in spiral arms seem to be responding to much more mass than is visible here, implying that galaxies are predominantly composed of some sort of dark matter. Finding the nature of this dark matter remains one of the great challenges of modern science.