Emission nebulae IC 1805 and IC 1848. North is at top. These nebulae are also known as the Heart and Soul nebulae. The Soul nebula (IC 1848) is at lower left, with the Heart nebula (IC 1805) at centre right. These are huge clouds of gas and dust that glow as the hydrogen they contain is ionised by radiation from the hot young stars that have formed within them. The centre of the Heart nebula contains the open star cluster Melotte 15, which illuminates the surrounding nebula. The cluster contains around 40 stars, all of which formed just 1.3 million years ago, very young in stellar terms. The nebulae lie around 7000 light years from Earth in the constellation Cassiopeia. Photographed by the 1.22-metre Oschin Telescope at Mount Palomar, California, USA.