Supernova May Have Left Its Mark In Iron-Eating Bacteria Preserved As Fossils

16/04/2013 12:07 BST

Despite its effects reaching Earth over 2.2 million years ago - and potentially having enough energy to outshine an entire galaxy - a supernova may have left its mark in the most unlikely of places.

Scientists examining a core sample from deep below the Pacific Ocean found traces of an iron isotope that does not form on Earth.

Their conclusion? The extraterrestrial isotope was blasted towards Earth in a supernova where it was gobbled up by iron-hungry bacteria and preserved in the fossil record when they died.


Supernovas happen around once every 50 years in a galaxy the size of ours

Shawn Bishop, a physicist at the Technical University of Munich in Germany who worked on the project said: "For me, philosophically, the charm is that this is sitting in the fossil record of our planet," reported the Nature journal.

A supernova is essentially the death of a large star when its core undergoes sudden and catastrophic nuclear fusion, blasting material into space.

The iron isotope found in the core sample, iron-60 is thought to be some of this material after it was hurled at the Earth close to the speed of light.

The core sample covered a period of 1.7 million to 3.3 million years ago and the trace signature was only present around the 2.2 million year mark, indicating a single event.

It is not known which star could have been responsible for this particular supernova although Nature suggests "suspects in the Scorpius–Centaurus stellar association, at a distance of about 130 parsecs (424 light years) from the Sun".

A special type of organism called magnetotactic bacteria consume iron in order to form tiny magnetic crystals within them.

They use these to align themselves with the Earth's magnetic field like a living compass thus helping them navigate.

Bishop and his team are now conducting the same tests on a second core to confirm the findings.