Dark patches in the Milky Way are really clouds of dust cutting out the light from the stars.The most famous one is called "The Coalsack". [银河中的暗淡部份其实是阻隔了可见光的星际尘埃,当中最著名的是暗黑星云「煤袋」。
The Coalsack Dark Nebula (or simply the Coalsack) is the most prominent dark nebula in the skies, easily visible to the naked eye as a dark patch silhouetted against the southern Milky Way. It is located at a distance of approximately 600 light years away from Earth, in the constellation Crux.