Astronomers have used the Very Large Telescope in Chile to image the ethereal gas cloud known as CG4.

VLT image of the cometary globule CG4 [credit: ESO]

It is an example of a ‘cometary globule’ – long, stretched out clouds of gas that are reminiscent of comets. They were first discovered in 1976 and their exact nature remains elusive. The new image shows the very top of CG4 which we can only see because it is illuminated by nearby stars. If the image extended further down it would get narrower as you went like a comet’s tail.

It is thought that these beautiful clouds were once spherical but something has interacted with them, causing them to stretch out. The two main suggested culprits are a nearby supernova explosion or intense stellar winds blowing from hot, massive stars.