The virus thought to cause Severe Acute Respiratory Syndrome - coronavirus - is so unlike any other known virus it can't be from Earth, they say.
But other scientists think the groups' theory is completely out of this world.
Pan what?
One of the scientists, Professor Chandra Wickramasinghe, says it's all to do with what's called the panspermia theory.
This idea says life came from somewhere in outer space and has moved from one planet to another by comets.
He says he doesn't have any proof that it is from space, and other Sars experts have been making fun of his ideas.
They insist there is nothing strange at all about the Sars coronavirus and that it developed from other known viruses.
The World Health Organisation say they are not planning to send a Sars inspection team into outer space just yet.
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