Scientists studying freshly fallen snow in Antarctica have uncovered a rare isotope of iron inthe interstellar dust hidden inside it, suggesting the dust showed up recently.
This discovery could give us crucial information about the history of stellar explosions in ourgalactic neighbourhood.
We know that cosmic dust is drifting down to Earth all the time, tiny bits of debris from therough and tumble of star and planet formation, sometimes billions of years old.
Antarctica is a great place to look for such dust, because it's one of the most unspoilt regionson Earth, making it easier to find isotopes that didn't originate on our own planet.
In this case, the isotope that researchers have pinpointed is the rare 60Fe (or iron-60), one ofmany radioactive variants of iron.
Previously, the presence of this iron in deep-sea sediment and fossilised remains of bacteriahas suggested one or more supernovae exploded in Earth's vicinity between 3.2 and 1.7 millionyears ago.
The new study marks the first time interstellar iron-60 has been detected in recent Antarcticsnow - the dust would have fallen from the skies within the last 20 years, the researchers say.
"I was personally very surprised, because it was only a hypothesis that there might be iron-60 and it was even more uncertain that the signal is strong enough to be detected," nuclearphysicist Dominik Koll from Australian National University told ScienceAlert.