Back to Glossary

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"

IC 2574: Coddington's Nebula

06/02/2025

IC 2574: Coddington's Nebula
Image Credit: Lorand Fenyes / NASA APOD

Grand spiral galaxies often seem to get all the glory, flaunting their young, bright, blue star clusters in beautiful, symmetric spiral arms. But small, irregular galaxies form stars too. In fact dwarf galaxy IC 2574 shows clear evidence of intense star forming activity in its telltale reddish regions of glowing hydrogen gas. Just as in spiral galaxies, the turbulent star-forming regions in IC 2574 are churned by stellar winds and supernova explosions spewing material into the galaxy's interstellar medium and triggering further star formation. A mere 12 million light-years distant, IC 2574 is part of the M81 group of galaxies, seen toward the northern constellation Ursa Major. Also known as Coddington's Nebula, the lovely island universe is about 50,000 light-years across, discovered by American astronomer Edwin Coddington in 1898.