Starfield centred on the constellation of Musca, showing a densely populated area of our galaxy, the Milky Way. The two brightest stars at centre are alpha (centre) and beta (upper centre left) Muscae. The dark areas seen at top centre are part of the Coal Sack Nebula, a large dark nebula in the constellation of Crux; it is formed by a cloud of interstellar dust absorbing the radiation emitted by stars embedded in it. Another dark nebula (thin and elongated) is seen at lower centre.