Discover the cosmosEach day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Explanation:The small, northern constellation Triangulumharbors 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 Groupof galaxies after the Andromeda Galaxy, and our own Milky Way.
About3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy andastronomersin these two galaxies would likely have spectacular views of each other’s grand spiral star systems.
As for the view from the Milky Way, thissharp telescopic imageshows off M33’s blue star clusters and pinkishstar formingregions along the galaxy’s loosely wound spiral arms.
In fact, thecavernous NGC 604is 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 forestablishingthe distancescale of the Universe.
APOD’s main NASA site ismoving:Fromapod.nasa.govtoscience.nasa.gov/apod Tomorrow’s picture:star party weekend