More images of our visitor from another star system have been released after it was spotted doing something a bit odd.
3I/ATLAS could be the most famous space rock ever (you’ve already forgotten 2024 YR4, right?) as it’s making headlines for ‘pulsing’.
The giant dirty snowball has been seen dimming and brightening, akin to a ‘heartbeat’, according to one Harvard astrophysicist.
Now, Nasa and its European counterpart have released new images of 31/ATLAS ahead of its close encounter with Earth on December 19.
The Hubble Space Telescope snapped the comet when it was about 178 million miles away from Earth on November 30.
The image shows the comet as a white dot, with the glow caused by sunlight bouncing off a plume of gas and dust known as a coma.
Comets get brighter and brighter as they zip closer to the Sun, as the ice turns into vapour, which the European Space Agency (ESA) captured.
The Jupiter Icy Moons Explorer (Juice) orbiter was just 41 million miles away from 3I/ATLAS when it took a photo on November 2.
The ESA wrote ‘Not only do we clearly see the glowing halo of gas surrounding the comet known as its coma, we also see a hint of two tails.
‘The comet’s “plasma tail” – made up of electrically charged gas, stretches out towards the top of the frame.
‘We may also be able to see a fainter “dust tail” – made up of tiny solid particles – stretching to the lower left of the frame.’
Space officials say that as 3I/ATLAS approaches Earth, these sightings will help them learn more about what this cosmic lump of ice and dirt is.
‘If it’s a heartbeat, then those aliens are really, really, super chill’
Between the images of glowing smears and barely visible dots, some things the comet has been spotted doing are on the strange side.
Harvard astrophysicist Dr Avi Loeb said last week that jets are coming from the comet once every 16.16 hours.
Loeb suggested that this ‘heartbeat’ is evidence of an alien craft manoeuvring around the solar system.
He did acknowledge that a natural explanation was possible, but said it also might be a way for the object to deliberately manoeuvre.
But Dr Matthew Genge, a micrometeorite and cosmic dust specialist at Imperial College London, told Metro: ‘There’s a periodic brightening of the comet. That’s actually nothing particularly unusual.
‘It happens once every 16 hours, so if it’s a heartbeat, then those aliens are really, really, super chill, because that’s incredibly slow.’
Dr Genge said while he was happy we’re all thinking so much about the comet, the ‘media frenzy’ around it was ‘ludicrous’ and there’s still no reason to think it’s anything more than a dirty snowball in space.
So what is causing the pulsing?
The main theory is that there could be a particularly volatile patch of ice on its surface, which turns to gas at a low temperature.
When the comet rotates this patch into the sunlight, it heats up and blasts out dust and gas, also known as jets.
Dr Genge said we can’t actually see the nucleus – the solid part of the comet – because it’s producing so much gas. He added: ‘It’s like trying to see a white cat in fog.’
Even if we can’t see the icy patch to prove it, it’s the most likely explanation, as many comets have had this periodic brightening before.
Dr Genge joked: ‘I would be more impressed if it was brightening periodically and beeping while it did it, because then it might be about to go into reverse.’
He added: ‘It just reinforces that it’s behaving like a comet. It looks like a comet, it behaves like a comet… therefore, it’s most likely a comet.’
Are interstellar comets like buses?
Even if 3I/ATLAS is ‘just’ a comet, it’s still one thought to be billions of years older than our own star.
Scientists are excited about the possibility of one day landing on an interstellar comet and examining part of it in a lab, but so far, we have only ever seen three.
Until the first one, Oumuamua, was spotted in 2017, they were thought to be incredibly rare.
Since then, another two have appeared, indicating they are more common than we realised and we are just getting better at spotting them.
Dr Genge said three is still not enough to give reliable statistics on how frequently we should expect them to appear. ‘We’ve all sat waiting for buses, haven’t we? Three can come at once,’ he said.
But he added that it does suggest more rocks are thrown out of other planetary systems than we previously assumed.
At least four more months of speculation
Once comets pass further from the Sun than the orbit of Jupiter, they tend to become less active and less bright.
This one is expected to get there around March 16 next year, and it’s a safe bet that it will be eagerly tracked both by astronomers and those who believe the truth is out there.
Dr Loeb has claimed that 3I/ATLAS will pass so close to the gas giant that it could ‘release technological devices as artificial satellites of Jupiter’.
But it won’t be captured within its orbit to become a permanent visitor. It is expected to pass back on our of our solar system and into outer space.
However, it was potentially an interaction with another giant planet which initially threw the rock out of its own part of the galaxy.
‘Jupiter is a bit of a bully, and if asteroids or comets encounter it, it can do a gravitational slingshot and literally shoot them out of the solar system,’ Dr Genge said.
‘Maybe that [type of interaction] happens more commonly than we previously thought, which would fit with there being quite a few giant planets around other stars.’
The comet will pass its closest to Earth on December 19, but it will still be very far away – around 170million miles, or twice the distance of the Sun.
And after that?
‘When it actually leaves and nothing happens, we’ll stop talking about it,’ Dr Genge said.
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