Heart Nebula

The Heart Nebula glows with a distinct red color because it is an emission nebula energized by ionized hydrogen gas. A cluster of massive, young, hot stars at its center, known as Melotte 15, emits immense amounts of ultraviolet radiation. This radiation strips electrons from the hydrogen atoms, causing the surrounding gas cloud to emit light in the red end of the spectrum.

The Heart Nebula is located in the constellation Cassiopeia, sitting about 7,500 light-years away from Earth. It lies in the Perseus Arm of the Milky Way galaxy. It is situated very close in the sky to the Soul Nebula, leading astronomers to frequently image them together as the 'Heart and Soul' pair.

The Heart Nebula is officially designated as IC 1805 in the Index Catalogue of nebulae. It is also listed as Sharpless 2-190 (Sh2-190) in the Sharpless catalog of H II regions. Its central star cluster is separately cataloged as Melotte 15.

The Heart Nebula was discovered by the prominent German-British astronomer William Herschel on November 3, 1787. Herschel is famous for his expansive deep-sky surveys, during which he discovered thousands of celestial objects. His sister Caroline Herschel was also a vital part of the observational process.