As the third interstellar object to be observed passing through our solar system gets closer, some scientists are flagging that certain details of this thing have them wondering.
The object hurtling through space is known as 3I/ATLAS, and it has travelled a very long way to get here, with most researchers reckoning that it's some sort of comet that first started heading our way a long time ago.
However, others have suggested it might be something else, as Professor Avi Loeb of Harvard University said his observations suggested it was 'a reflecting surface that is about 20 kilometres in diameter'.
He also has some other things to say about 3I/ATLAS, as Professor Loeb has raised the possibility that the interstellar object is not a chunk of rock that has been hurtling through space for billions of years, but an alien vessel containing extraterrestrials.
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Studying a recent image taken of the interstellar object by the Hubble Space Telescope last month, he is trying to figure out why it looks like it's glowing.
He suggested that if the interstellar object generates its own light, then it could be smaller than his previous estimate, with NASA's own observations suggesting it is smaller than first thought, and argues that 'illumination by sunlight cannot explain' the scattered light.
As for what it could be, Professor Loeb suggested 3I/ATLAS could contain a 'natural nuclear source', but said this was quite unlikely. The scientist also suggested it might be a spacecraft with nuclear energy powering it, which would mean it was an alien vessel travelling through our solar system.
While the path it takes will carry it beyond Earth, it is not on course to hit us, though Loeb suggested this 'could be intentional to avoid detailed observations from Earth-based telescopes'.
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He said that if it is alien, then it's 'potentially hostile', though his best estimation is that it's 'a completely natural interstellar object', so it's probably not aliens.
But it could be...
NASA experts believe 3I/ATLAS is a comet and have predicted that it will pass through our solar system in the coming months.
However, they're pretty sure it's not going to come close to Earth, with the closest it's expected to get being about 170 million miles away from our planet.
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Meanwhile, it will get closer to the sun on 30 October this year, coming within around 130 million miles.
If it really is aliens, then they're either going to have to change direction very quickly, or they're just going to do a drive-by. At the same time, if it's a comet, then nobody but the laws of physics is at the wheel, and we should be very glad this fast-moving interstellar object is going to miss us.
The closer 3I/ATLAS gets, the clearer the view we get of it, though eventually it'll become impossible to see thanks to the sun before becoming visible again in December.
Joe Harker