APOD: 2026 September 18 – Messier 33: The Triangulum Galaxy
The post APOD: 2026 September 18 – Messier 33: The Triangulum Galaxy appeared first on NASA Science .
On September 18, 2026, the Astronomy Picture of the Day (APOD) featured a stunning image of Messier 33, also known as the Triangulum Galaxy. This face-on spiral galaxy resides in the small, northern constellation Triangulum and boasts a diameter of over 50,000 light-years, making it the third largest galaxy in the Local Group, after the Andromeda Galaxy (M31) and our Milky Way.
Located approximately 3 million light-years from the Milky Way, M33 is believed to be a satellite of the Andromeda Galaxy, offering both galaxies a breathtaking view of each other's grand spiral star systems.
The APOD image showcases M33's vibrant blue star clusters and pinkish star-forming regions along its loosely wound spiral arms. Within this cosmic wonder, the cavernous NGC 604 stands out as the brightest star-forming region, situated at about the 5 o'clock position from the galaxy center. Similar to its larger counterpart, the Andromeda Galaxy, M33's population of variable stars has aided astronomers in establishing a cosmic yardstick for measuring the distance scale of the Universe.
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- APOD: 2026 September 18 – Messier 33: The Triangulum Galaxy science.nasa.gov
