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"

M77: Spiral Galaxy with an Active Center

02/12/2025

M77: Spiral Galaxy with an Active Center
Image Credit: NASA Astronomy Picture of the Day

What's happening in the center of nearby spiral galaxy M77? The face-on galaxy lies a mere 47 million light-years away toward the constellation of the Sea Monster (Cetus). At that estimated distance, this gorgeous island universe is about 100 thousand light-years across. Also known as NGC 1068, its compact and very bright core is well studied by astronomers exploring the mysteries of supermassive black holes in active Seyfert galaxies. M77's active core glows bright at x-ray, ultraviolet, visible, infrared, and radio wavelengths. The featured sharp image of M77 was taken by the Hubble Space Telescope. The image shows details of the spiral's winding spiral arms as traced by obscuring red dust clouds and blue star clusters, all circling the galaxy's bright white luminous center. Free APOD Lecture in Phoenix: Wednesday, December 10 at 7 pm