For Halloween, the European Southern Observatory (ESO) reveals this spooktacular image of a dark nebula that creates the illusion of a wolf-like silhouette against a colourful cosmic backdrop. Fittingly nicknamed the Dark Wolf Nebula, it was captured in a 283-million-pixel image by the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile.
Found in the constellation Scorpius, near the centre of the Milky Way on the sky, the Dark Wolf Nebula is located around 5300 light-years from Earth. This image takes up an area in the sky equivalent to four full Moons, but is actually part of an even larger nebula called Gum 55. If you look closely, the wolf could even be a werewolf, its hands ready to grab unsuspecting bystanders…
If you thought that darkness equals emptiness, think again. Dark nebulae are cold clouds of cosmic dust, so dense that they obscure the light of stars and other objects behind them. As their name suggests, they do not emit visible light, unlike other nebulae. Dust grains within them absorb visible light and only let through radiation at longer wavelengths, like infrared light. Astronomers study these clouds of frozen dust because they often contain new stars in the making.
Of course, tracing the wolf’s ghost-like presence in the sky is only possible because it contrasts with a bright background. This image shows in spectacular detail how the dark wolf stands out against the glowing star-forming clouds behind it. The colourful clouds are built up mostly of hydrogen gas and glow in reddish tones excited by the intense UV radiation from the newborn stars within them.
Some dark nebulae, like the Coalsack Nebula, can be seen with the naked eye — and play a key role in how First Nations interpret the sky [1] — but not the Dark Wolf. This image was created using data from the VLT Survey Telescope, which is owned by the National Institute for Astrophysics in Italy (INAF) and is hosted at ESO’s Paranal Observatory, in Chile’s Atacama Desert. The telescope is equipped with a specially designed camera to map the southern sky in visible light.
The picture was compiled from images taken at different times, each one with a filter letting in a different colour of light. They were all captured during the VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+), which has studied some 500 million objects in our Milky Way. Surveys like this help scientists to better understand the life cycle of stars within our home galaxy, and the obtained data are made publicly available through the ESO science portal. Explore this treasure trove of data yourself: who knows what other eerie shapes you will uncover in the dark?
Note
[1] The Mapuche people of south-central Chile refer to the Coalsack Nebula as ‘pozoko’ (water well), and the Incas called it ‘yutu’ (a partridge-like bird).
