The Southern Sky in Warm Hydrogen
A robotic telescope with red sunglasses in Chile has been photographing the entire southern sky for years. The result, shown above , is the most complete sky map of the most common visible light emitted from the most abundant element in our Galaxy : hydrogen . A very specific red color emitted by warm ionized hydrogen was observed. Although spectacular emission nebula s glow brightly in this type of red light ( H-alpha ), a diffuse amount of warm hydrogen is spread throughout our Galaxy and its glow nicely indicates not only where darker hydrogen and other gasses may be located, but also the sometimes- complex history of interstellar gas . Gas tracking the plane of our Galaxy runs across the center, and huge gas clouds , some of which are the expanding shells of long dead stars , are also visible. The above map was derived from the Southern H-Alpha Sky Survey Atlas (SHASSA) and shows that our entire Galaxy is one big emission nebula , albeit at a quite faint level.