New ESO image captures a dark wolf in the sky

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.

This collage highlights some details within the huge Dark Wolf Nebula, such as the wolf’s “head”, seen here in the top-centre image. The pillars in the images to the right form when intense radiation from young stars encounters dense pockets of dust and gas. This radiation erodes and blows away the lighter material around these dense pockets, creating these pillar-like structures. Credit: ESO/VPHAS+ team

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…

This chart shows the location of the Dark Wolf Nebula in the constellation Scorpius (the Scorpion). This map shows most of the stars visible to the unaided eye under good conditions. The location of the nebula itself is marked with a red circle. Credit: ESO, IAU and Sky & Telescope

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 –– 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? (ESO)