TRANSCRIPT
In just a matter of months, millions of people went from questioning whether there is other life in the Universe, to seemingly believing there is.
It was thanks to a Harvard professor's view that an alien mothership with hostile aliens aboard, disguising itself as a comet, was headed to Earth, to either show us a better way of life or enslave us all.
Ridiculous maybe, or out of this world?
NASA thinks so.
Since its discovery in July, 3I/ATLAS has fascinated the world after Harvard University astrophysicist and renowned alien-hunter Avi Loeb voiced a theory, without providing any evidence, that the comet may actually be an alien spacecraft in disguise.
To astronomers, the claim is all too familiar.
Jonti Horner, an astrobiologist and astronomer at the University of Southern Queensland, says it echoes the public panic Loeb triggered during the discovery of the first interstellar object, Oumuamua.
"It's like the famous story of the boy who cried wolf, except in this case, there is no wolf. So this is not the first time that this Harvard professor who is not, historically, a solar system astronomer or an astrobiologist, it should be said, has come out with this. Back when the first interstellar object Omuamua was discovered in 2017, for the entire period we were studying that he was getting a huge amount of media saying all the scientists are wrong. This is an alien space ship. And of course, it wasn't."
NASA knew it had to address this, especially as rumours swirled of a cover-up when the US space agency stayed silent.
That silence was due to the US government shutdown, but now that's over, NASA has held a press conference to set the record straight.
Amit Kshatriya is a NASA associate administrator.
"We're here today to give you the latest of what we know about Comet 3I/ATLAS and what we still want to know. But first, what is a comet? It's a small, natural solid body that is a combination of rocky and icy material that evaporates as it warms when it's close to a star like the sun. ... This object is a comet. It looks and behaves like a comet and all evidence points to it being a comet, but this one came from outside the solar system, which makes it fascinating, exciting, and scientifically very important. This is only the third interstellar object like this that humanity has ever found."
With rumours spreading quickly, NASA’s Planetary Defence Coordination Office analysed ATLAS's path through our solar system and confirmed there is no risk of impact, no unusual thrust, and no controlled motion.
Made up of rock, dust, ice and gas - the comet is also what's called a "dirty snowball".
NASA says 18 spacecraft are now observing 3I/ATLAS, among them Hubble and JWST to Perseverance, MAVEN, Lucy, Psyche, SOHO and the Parker Solar Probe.
The comet’s velocity and inbound trajectory strongly suggest it originated around a star formed long before our Sun.
Tom Statler is lead scientist at NASA's Solar System Small Bodies at NASA's Planetary Defence.
"There is circumstantial evidence, given how fast it has come in to our solar system that it came from some very old population, some solar system around a very old star. Quite possibly, we can't say this for sure, but the likelihood is it came from a solar system older than our own solar system itself, which gives me goosebumps to think about, frankly, because that means the 3I/ATLAS is not just a window into another solar system, it's a window into the deep past and so deep in the past that it predates even the formation of our Earth and our Sun."
Excitement spiked when South Africa’s MeerKAT telescope detected the first radio emissions from an interstellar comet, briefly convincing parts of the internet that 3I/ATLAS was phoning home.
In reality, the signal was nothing more glamorous than hydroxyl radicals, water blasted from the comet and split by sunlight, precisely the behaviour NASA had already observed when it noted 3I/ATLAS spraying water like a fire hose.
At the point of its closest approach to Sun - in late October - the comet brightened, changed colour and seemed to lose its tail, sending social media into full meltdown.
But astronomers quickly showed the tail was never gone. We were simply looking at it from a tricky angle, with dust and glare doing the rest.
Features touted as alien, from its anti-tail to its irradiated surface and excess carbon dioxide, all have well-understood, entirely natural explanations.
Even the rumour that a separate comet, C/2025 V1 (Borisov), was a probe deployed by 3I/ATLAS collapsed on contact with basic astronomy.
Borisov is just a garden-variety solar system comet, unrelated to the interstellar traveller.
And those claims that ATLAS is zig-zagging towards Earth?
NASA’s Tom Statler notes it is simply outgassing nudging it around, the celestial equivalent of a sprinkler rotating itself on a lawn.
"Every time something gets pushed off the comet, that acts like a little rocket engine at that moment and pushes in the other direction. And so it's very, very common to see comets have subtle changes in their orbits as a result of these little rocket forces just called non-gravitational acceleration. ... But so far the non-gravitational accelerations have been very much on par with the sort that we see in solar system comets."
So again, nothing artificial, nothing controlled.
Jonti Horner, the University of Southern Queensland astrobiologist and astronomer, says the science is unequivocal.
"Atlas is a comet. It looks like a comet. It behaves like a comet. It's a comet. There is nothing about it to suggest that it is anything other than a natural object."
But he says the conspiracy theories have had real-world consequences.
Professor Horner says he has heard from people who were genuinely panicked by the claims.
"The other thing that's really bad about this is that it's genuinely got people terrified. I've had people contacting me, friends, relatives, friends of friends, when these stories were coming out, who were genuinely worried that aliens were coming to attack the earth. A guy from Harvard told us this, what should we do? Is this really true? And it wasn't scientific inquiry that was driving them. It was fear. They were frightened."
3I/ATLAS is now around 304 million kilometres away and visible in the predawn sky with a professional telescope.
It will make its closest approach to Earth in mid-December, still a safe 267 million kilometres away, before leaving the solar system forever.
This is humanity’s only chance to study it.
And if you are hoping to catch a glimpse, Mr Horner says it is possible, but challenging.
"It is a morning object. I think currently it looks like it will be somewhere near it will be in Virgo at the minute. So, it looks like this comet is visible in the morning sky before sunrise, but I will reaffirm that it is significantly too faint to see with the naked eye. You do need a telescope to see this. ... So for me here in Toowoomba, it would rise at about 2am which means you have a few hours before dawn to see it, and because it's in Virgo, it's pretty much bang on the equator. That means it's visible from anywhere on the planet in the morning sky before sunrise."
So, from radio signals to water jets, colour changes to ancient chemistry, 3I/ATLAS continues to astonish astronomers - not because it’s alien, but because it’s one of the oldest natural objects we have ever encountered, forged in a star system that may have vanished billions of years ago.
