A large emission nebula in Cassiopeia, about 7,500 light-years away, whose overall shape in wide-field images resembles a human heart. The nebula is powered by a cluster of hot, young O-type stars near its centre — Melotte 15 — whose radiation ionises the surrounding gas and whose stellar winds carve dramatic pillars and ridges into the cloud. These pillars, visible in the nebula's core, are reminiscent of the famous Pillars of Creation in the Eagle Nebula, though less well known.

Together with the neighbouring Soul Nebula (IC 1848), the Heart forms one of the most recognisable pairs in the northern sky, and the region is a rich target for narrowband imaging.