One of the biggest blasts in our galaxy went off without anyone spotting it because it was hidden behind a cloud of dust, astronomers revealed today.
The explosion, a suicidal star called a supernova, was brighter than all the stars in the Milky Way combined and might normally have been visible in daylight.
However, Victorian stargazers saw nothing of the blast around 150 years ago due to a dense region of obscuring dust and gas.
Remnants of its expanding shell have finally been identified by UK scientist Dr Dave Green, of the University of Cambridge, with colleague Dr Stephen Reynolds of North Carolina State University.
Experts had often remarked on the fact that no supernova had been recorded within our galaxy since the 17th Century, although they are regularly spotted going off in other galaxies deep in the universe.
The two scientists compared an X-ray “photo” of the blast’s remains taken using the Chandra satellite in 2007 with another image made with a group of US radio telescopes called the Very Large Array in 1985.
They found the supernova remnant, called G1.9+0.3, had expanded at an unprecedented rate, growing in size by 15 per cent in just 23 years. Working backwards, they confirmed that the blast that created them must have happened about 150 years ago.
This finding makes the supernova easily the youngest known in our Milky Way galaxy. Although its precise distance is not known, the astronomers believe it lies near the centre of the galaxy.
Radio waves and Xrays are able to penetrate dense clouds of dust whereas light cannot. Dr Green said: “The discovery that G1.9+0.3 is so young is very exciting. It fits into a large gap in the known ages of supernova remnants, and since it is expanding so quickly, we will be able to follow its evolution over the coming years.”
Details of the discovery will appear in the journal Monthly Notices of the Royal Astronomical Society. Planets like our own are believed to form from dust left by supernova blasts.
The closest supernova to us in recent years was seen to explode in 1987 in a satellite galaxy of the Milky Way called the Large Magellanic Cloud. It became easily visible with the naked eye and its debris was later pictured shining like a ring of pearls. Last month, astronomers identified clusters of other candidates for supernovae.