APOD: 2026 September 18 – Messier 33: The Triangulum Galaxy - NASA Science

APOD Science APOD APOD: 2026 September 18 –… Today’s APOD Archive Submissions Index Search Calendar RSS Education About Discuss APOD Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Messier 33: The Triangulum Galaxy Explanation: The small, northern constellation Triangulum harbors this magnificent face-on spiral galaxy, Messier 33. Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33 is over 50,000 light-years in diameter, third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and our own Milky Way. About 3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy and astronomers in these two galaxies would likely have spectacular views of each other’s grand spiral star systems. As for the view from the Milky Way, this sharp telescopic image shows off M33’s blue star clusters and pinkish star forming regions along the galaxy’s loosely wound spiral arms. In fact, the cavernous NGC 604 is the brightest star forming region, seen here at about the 5 o’clock position from the galaxy center. Like M31, M33’s population of well-measured variable stars have helped make this nearby spiral a cosmic yardstick for establishing the distance scale of the Universe. APOD’s main NASA site is moving: From apod.nasa.gov to science.nasa.gov/apod Tomorrow’s picture: star party weekend Date September 18, 2026 Credit & Copyright: George Chatzifrantzis Authors & editors: Jerry Bonnell, Cecilia Chirenti, Robert Nemiroff, Keighley Rockcliffe A service of: ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. Random APOD Generator Yesterday’s Image APOD: 2026 September 17 – A Treasure Chest in the Carina Nebula Tomorrow’s Image — Company newsroom — sourced from NASA. Matter furnished by the company. Not a Notice Nearby paid placement. This page reprints matter furnished by the company from its official newsroom. Notice Nearby did not write this release. Read the original: https://science.nasa.gov/image-article/apod-2026-september-18-messier-33-the-triangulum-galaxy