An international team of scientists has discovered evidence of a series of massive supernova explosions near our solar system, which showered the Earth with radioactive debris.
The scientists found radioactive iron-60 in sediment and crust samples taken from the Pacific, Atlantic and Indian Oceans.
The iron-60 was concentrated in a period between 3.2 and 1.7 million years ago, which is relatively recent in astronomical terms, said research leader Dr Anton Wallner from The Australian National University (ANU).
“We were very surprised that there was debris clearly spread across 1.5 million years,” said Dr Wallner, a nuclear physicist in the ANU Research School of Physics and Engineering. “It suggests there were a series of supernovae, one after another.
The team from Australia, the University of Vienna in Austria, Hebrew University in Israel, Shimizu Corporation and University of Tokyo, Nihon University and University of Tsukuba in Japan, Senckenberg Collections of Natural History Dresden and Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Germany, also found evidence of iron-60 from an older supernova around eight million years ago, coinciding with global faunal changes in the late Miocene.
A supernova is a massive explosion of a star as it runs out of fuel and collapses.
The scientists believe the supernovae in this case were less than 300 light years away, close enough to be visible during the day and comparable to the brightness of the Moon.
Although Earth would have been exposed to an increased cosmic ray bombardment, the radiation would have been too weak to cause direct biological damage or trigger mass extinctions.
The supernova explosions create many heavy elements and radioactive isotopes which are strewn into the cosmic neighbourhood.
PM congratulates Nepali national cricket team
KATHMANDU— Prime Minister KP Sharma Oli has congratulated Nepali national cricket team for being able to clinch the International T20 series.
PM Oli in a tweet extended best wishes and congratulations saying he was very happy to know Nepal’s win over the UAE by 14 runs in the third match of the series.
Winning T20 series is another landmark success for Nepali cricket, he said, adding, “It is big achievement for Nepal’s cricket. I would like to heartily congratulate entire members of Nepali cricket squad”.