Galaxy season approaches
Most of us look forward to spring because we are tired of the cold and long to see the rebirth of life with flowers blooming and hummingbirds returning from their long vacation in Mexico. Astronomers like springtime because that’s when nearby large groups of galaxies “bloom” like flowers in the night sky. NGC 2903 is the vanguard of these cosmic flowers. It’s surprisingly bright as galaxies go and can be observed through a high power eyepiece attached to a 6-inch backyard telescope.
NGC 2903 was overlooked by Charles Messier when he compiled his famous list of 109 deep space objects. I don’t know how he missed it because other objects on his list are much dimmer and harder to see. When it finally was cataloged by William Herschel (discoverer of planet Uranus) on Nov. 16, 1784, it was still missed in a way because Herschel didn’t know what he was looking at. Galaxies were unknown until Edwin Hubble discovered what they were, nearly 140 years later.
NGC 2903 is a barred spiral galaxy with two enormous sweeping spiral arms emanating from the edges of its central Hershey bar shaped structure. The spiral arms are wound very tight near the galactic center, but unfold like two large flower petals as they spread outward into intergalactic space. The colors depict various stages of star formation. Blue shows mostly young very hot star clusters. Red indicates massive hydrogen clouds glowing from newborn stars. The yellow hue is from aging stars normally found in the inner regions of most galaxies. Brown displays the thick dark dust lanes found in and between the spiral arms. What’s very unusual is the presence of four large young blue star clusters located practically at the galactic center. One explanation could be that there was a merger between NGC 2903 and another galaxy in eons past that jumbled older stars with new star-forming regions.