Astrobiologists believe they have found evidence of extraterrestrial life in our planet's atmosphere.
Back in September, a group of astrobiologists led by Professor Milton Wainwright hit the headlines when they announced they had found biological particles high in the stratosphere, in the outer region of our planet's atmosphere.
The researchers suggested that these particles may be the first direct evidence of the existence of extraterrestrial life forms in other parts of the universe. The team is now back in the spotlight, revealing new details about their exploration of what they now call "ghost particles."
Wainwright and colleagues speculate that these microscopic biological structures could be tiny living "balls" that alien microorganisms can "inflate" and use to move through the planet's atmosphere.
"The particles we found are definitely of biological origin," the team writes. "We can assume that in its space environment, this 'particle ghost' is a living ball that allows alien microscopic organisms to float in the air or other unknown outer space."
This latest study follows the recent discovery by Russian cosmonauts of diatomic plankton on the surface of the International Space Station, which in itself indicates the ability of Earth's microorganisms to travel through space and transfer life to other planets.
However, Wainwright's team strongly believes that the "particle ghosts" are not of Earth origin.
"These particles were found in absolutely perfect condition, without any contamination such as pollen, grass or other biology from our planet," the researchers write.
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"Since there is no means of lifting them from the Earth, they must have come to us from space."