The Soul Nebula houses several open clusters of stars, a large radio source known as W5, and huge evacuated bubbles formed by the winds of young massive stars. Located about 6,500 light years away, the Soul Nebula spans about 100 light years and is usually imaged next to its celestial neighbor the Heart Nebula (IC 1805). This picture appears mostly red due to the emission of a specific color of light emitted by excited hydrogen gas.
Image Credit & Copyright: Bob Andersson
Explanation from: http://apod.nasa.gov/apod/ap130415.html