Bright from the Heart Nebula . ... Image Copyright: Simon Addis Explanation: What's that inside the Heart Nebula? ... The nebula glows brightly in red light emitted by its most prominent element: hydrogen . ... In the center of the Heart Nebula are young stars from the open star cluster Melotte 15 that are eroding away several picturesque dust pillars with their energetic light and winds. ... The Heart Nebula is located about 7,500 light years away toward the constellation of Cassiopeia . ...