Researchers discovered a rare radioactive plutonium isotope nearly 5,000 feet below the Pacific Ocean, opening more questions about the origin of Earth.
This dangerous plutonium isotope is called the plutonium-244, which likely is the result of "violent cosmic events" that happened millions of years ago, Today UK News reported.
The presence of this dangerous element on Earth could mean that an exceptionally violent event has happened in space leading to its formation.
Study lead author Anton Wallner of The Australian National University said that the formation of plutonium-244 is complicated. It could be produced in supernova explosions or could be leftover from a much older neutron star.
But aside from plutonium-244, they also discovered iron-60.
Plutonium On Earth
It is extremely rare to see plutonium on Earth. Currently, the plutonium found in the environment is a result of human activities such as the testing of nuclear weapons in the atmosphere. They are so rare in nature because of being radioactive, they decay with a characteristic half-life, Scientific American reported.
But that does not mean that they do not occur naturally. Although extremely rare, they can also be found naturally in some places on Earth.
According to the Science News website, plutonium occurs naturally but at very low concentrations. It is not observable except when using ultra-sensitive modern analytical techniques.
All heavy metals found on Earth were formed as a result of nuclear reactions during supernova explosions dating back millions of years before Earth has even formed. Elements formed at that time with a half-life of 4.5 billion years have most likely have decayed already.
Supernova Produced Plutonium Isotopes
According to the Daily Mail, scientists dated the two elements found deep in the Pacific Ocean and confirmed that it was indeed the plutonium-244 and iron-60. Both of these elements formed around four billion years ago during the Earth's formation.
"Our data could be the first evidence that supernovae do indeed produce plutonium-244," Wallner said in a statement in the news release of the university published in ANSTO.
Comparing the two elements, iron-60 has a half-life of eight million years but it could turn into nickel which is a valuable commodity. On the other hand, plutonium-244's half-life is 80 million years that is long enough for it to remain from the events over millions of years ago but shorter than the time of the Solar System's formation.
The study, "60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae" published in the journal Science, suggests that the plutonium-244 was once in the interstellar medium before the supernova explosions and was pushed across the Solar System together with other remnants of the explosive event.
Although many of these elements have already decayed into stable forms eons ago, the recent discovery of the radioactive plutonium isotope could imply that a supernova event from just a few millions of years ago has happened.
Further study on these isotopes could hopefully give insight to researchers to understand massive explosions in space that occurred in the Solar System million of years ago.
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