Forming the head of one of our most popular constellations in the Southern Hemisphere, “The Emu”, lies the Coalsack. This nebula appears as a dust cloud near the Southern Cross, blocking out the sky almost completely.
Nebula’s are formed by the dust and gasses from long-dead stars, but also signals rebirth as new stars are born from these same gasses. The dust particles gravitate with immense power towards each other, in order to create the required pressure for the birth of a star to commence. Nebula’s are extraordinary life-creating life forces and each react in a different manner to the light bodies that surround them. Some nebula’s, like the Coalsack, appear as dark patches against the sky, (absorbtion/dark nebula), others absorb heat from nearby stars and glow as effect (emission nebula) still others only reflect the light of the bodies that surround them (reflection nebula).
About the Coalsack
Running virtually the length of the Milky Way, lies the well-known constellation “The Emu”. The nebula at hand forms the head of the Emu, whilst the rest of the bird’s body can be seen as the shadow of the nebula extending to the ends of the Milky Way. The location of the Emu constellation acts as an indication of available seasonal foods. Carvings of Emu’s have been found scattered across Australia that line up with the Emu constellation. This correlates with the laying of the Emu’s eggs.
Different cultures have different interpretations for the Coalsack and the Emu. Some believe the dark patch to be a hole in one of the Milky Way’s rivers, whilst others believe the constellation and the nebula to be a pine tree with which one can ascend the heavens.
Did you Know?
Nebula’s can also be formed from stars that have died recently.
Smaller stars, like the Sun, can’t transform into a supernova, but the gasses expelled rather cause a planetary nebula. These nebula’s have nothing to do with planets as such, rather they were named “planetary” by William Herschel who named them based on their appearance almost 200 years ago.
The Coalsack lies almost 600 light-years from Earth and is 20 light-years across.
How to find the Coalsack
This nebula lies tucked between the brightest star (alpha Crucis) and Mimosa near the foot of the Southern Cross. The Coalsack then appears as a black patch of sky, above and to the right of the brightest star, Crucis.
Article by Genevieve Blignaut
Clarens News: January 2014