The nebulae – interstellar cloud of dust, hydrogen, helium and other ionized gases. Most nebulae are of vast size, some are hundreds of light years in diameter.
Many nebulae are visible due to their fluorescence caused by the embedded hot stars, while others are so diffuse they can only be detected with long exposures and special filters. Some nebulae are variably illuminated by Tauri variable stars. Nebulae are often star-forming regions, such as in the “Pillars of Creation” in the Eagle Nebula.