Strange nebula changes colour rhythmically like a mood lamp

A cloud of dust and gas in space, called a nebula, seems to be changing colour and brightness in a rhythmic way every four years, like a galactic mood lamp.

The VISTA telescope in the Atacama desert in Chile can survey large tracts of the Milky Way to look for extremely rare events in our galactic neighbourhood, such as supernova explosions, the most recent of which …