The Coalsack Nebula: the Black Magellanic Cloud

The Coalsack Nebula is located about 600 light-years away in the constellation of Crux — The Southern Cross. This huge object forms a conspicuous silhouette against the bright starry band of the Milky Way and has been known to people in the Southern Hemisphere for as long as our species has existed.

This image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope shows part of the huge cloud of dust and gas known as the Coalsack Nebula. The dust in this nebula absorbs and scatters the light from background stars.

Coalsack Nebula, or Caldwell 99, is a dark nebula — a dense cloud of interstellar dust that completely blocks out visible wavelengths of light from objects behind it. A significant number of the dust particles in dark nebulae are coated with frozen water, nitrogen, carbon monoxide, and other simple organic molecules. This results in visible light being prevented from passing through the cosmic cloud. The small amount of starlight that makes it through appears to be on the redder side of the light spectrum.

The inky Coalsack Nebula was first reported in Europe in 1499 by the Spanish explorer Vicente Yáñez Pinzón. The Coalsack later got the nickname ‘the Black Magellanic Cloud’, because of its dark appearance compared to the bright glow of the two Magellanic Clouds, satellite galaxies of the Milky Way. The two bright Magellanic Cloud galaxies are also clearly visible in the southern sky and came to the attention of Europeans during Ferdinand Magellan’s explorations in the 16th century.

Millions of years from now, parts of the Coalsack will ignite, rather like its fossil fuel namesake, glowing with the light of new young stars.

I first heard of the Coalsack Nebula when I was a very young child, reading Eagle Comics featuring the fearless Dan Dare! In other fictional works, this nebula is mentioned in the Star Trek: The Original Series episodes “The Immunity Syndrome” and “Let That Be Your Last Battlefield”, as well as 2001: A Space Odyssey by Arthur C. Clarke.