Space Dust on the Ocean Floor was Ejected by Ancient Supernovae

Two of the last unexplored frontiers are the deep ocean and the depths of space. Now, scientists are combining these two fields with a new discovery. They've found dust at the bottom of the ocean that may tell them a bit more about supernovae, the exploding stars beyond our solar system.

"Small amounts of debris from these distant explosions fall on the earth as it travels through the galaxy," said Anton Wallner, lead researcher of the new study, in a news release. "We've analyzed galactic dust from the last 25 million years that has settled on the ocean and found there is much less of the heavy elements such as plutonium and uranium than we expected."

Current theories of supernovae state that some of the materials essential for human life, such as iron, potassium and iodine, are created and distributed throughout space. Yet the galactic dust that the scientists discovered at the bottom of the ocean seems to indicate that this theory may be incorrect.

So how did the researchers know that the dust was actually from space? It all had to do with the elements it contained.

"Any plutonium-244 that existed when the earth formed from intergalactic gas and dust over four billion years ago has long since decayed," said Anton Wallner, one of the researchers, in a news release. "So any plutonium-244 that we find on earth must have been created in explosive events that have occurred more recently, in the last few hundred million years."

The fact that heavy elements like plutonium were present suggests that an explosive even must have happened close to earth around the time that it formed.

"Radioactive elements in our planet such as uranium and thorium provide much of the heat that drives continental movement, perhaps other planets don't have the same heat engine inside them," said Wallner.

The findings don't just reveal a bit more about our own planet, but also tell scientists a bit more about supernovae. Not only that, but it's possible that the Earth's oceans could contain more evidence for this type of space dust.

The findings are published in the journal Nature Communications.

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