... Bright Nebulae in M33 . ... Credit Copyright: Ken Crawford ( Rancho Del Sol Observatory ) Explanation: Gorgeous spiral galaxy M33 seems to have more than its fair share of bright emission nebulae. In fact, narrow-band and broad-band image data are combined in this beautifully detailed composite to trace the reddish emission nebulae, star forming HII regions , sprawling along loose spiral arms that wind toward the galaxy's core. ... Publications with keywords: emission nebula - star formation . ...