Merging black holes may have caused gamma-ray burst to hit Earth.
A powerful explosion in space that scientists think happened between the year 774 and 775 AD may have left evidence on Earth.
Tree rings of ancient cedars in Japan and ice deposits in Antarctica both show signs of rare isotopes that are created by heightened levels of radiation.
Some researchers think these are linked to a gamma ray burst that happened in our galaxy around this time.
A gamma ray burst is the most powerful type of explosion known to occur in the Universe.
It happens when two black holes or neutron stars collide, releasing an enormous amount of energy into space.
The people who were alive during the time of this gamma ray burst probably didn’t even notice, but the drastic increase in carbon 14 and beryllium 10 show that some cosmic event caused a reaction on Earth.
The radiation of this event would have been taken in by the atmosphere and only traces of the isotopes from the atmosphere actually made it into the trees and ice on the Earth’s surface.
Such a rise in these isotopes may have been caused by a solar flare, but it would have to have been 10 to 20 times stronger than any solar flares on record.