🌌 Cosmic blinding lights Caldwell 99 also known as the Coalsack is a dark nebula located within the constellation Crux, easily visible to the naked eye as a dark patch silhouetted against the southern Milky Way. Having been viewed by stargazers in the Southern Hemisphere for millennia, Caldwell 99 has no discoverer, but Europeans first learned of it from Spanish explorer Vicente Yáñez Pinzón in 1499. Caldwell 99 is located approximately 600 light-years from Earth and is about 100 light-years across. The dust in this nebula absorbs and scatters the light from background stars, making many of them appear fainter and redder. The interstellar dust is also so dense that it blocks out wavelengths of visible light from objects behind it. Credit: NASA, NASAHubble, ESA, & R. Sahai (Jet Propulsion Laboratory); Processing: Gladys Kober (NASA/Catholic University of America) #NASA #Sky #Coalsack #Nebula #Caldwell99 #Galaxy #SouthernCross #MilkyWay