An alien visitor passing through our solar system made its closest approach to Mars earlier this month, and two European robotic spacecraft orbiting the red planet turned to take a look.
3I/ATLAS is truly an alien visitor, having come from another solar system somewhere in the galaxy. It’s a comet which was cast away from its home star, perhaps due to a close encounter with a giant planet like Jupiter.
It then travelled for billions of years in interstellar space, was drawn into our solar system by the gravity of our sun, and is now passing through before it continues on its journey, never to return.
In fact, its trajectory suggests this could be the oldest comet ever discovered, making it potentially older than our 4.6 billion-year-old solar system.
Infographic showing the path of comet 3I/ATLAS through our solar system. (European Space Agency)The object will not come dangerously close to Earth, but it did pass within 30 million kilometers of Mars on Oct. 3. Two European Space Agency robots that are currently in orbit around Mars, ExoMars and Mars Express, were in the best position to capture images of 3I/ATLAS and revealed a fuzzy ball — known as a coma — with a short tail.
That suggests the object is like a comet with ices and dust that it gives off as they are heated by the sun.
Further analysis after it makes its closest approach to the sun on Oct. 30 should determine what those ices are made of and if they are similar to icy comets we have orbiting our sun.
WATCH | NASA Spacecraft Observe Interstellar Comet 3I/ATLAS as It Approaches Mars:
This is the third time an interstellar object has been spotted passing through our solar system after 1I/Oumuamua in 2017 and 2I/Borisov in 2019.
Each time the arrival of an alien object is announced, there is speculation that these could be alien spaceships that are either passing through with no interest in us whatsoever, or are here to deliver some kind of message.
The idea stems partially from a 1973 science fiction novel Rendezvous With Rama by Arthur C. Clarke, which chronicles the adventures of astronauts who catch up with a gigantic alien spaceship on a similar trajectory to find out what or who is inside.
So far, despite what some people on the internet are saying, there are no indications that 3I/ATLAS is a spaceship. It does not reflect light like a metallic object, there are no signals coming from it and a spacecraft would not give off a huge cloud of ice and dust (unless it was trying to disguise itself).
Of course, it would be much more interesting if the object was an alien spaceship, but it is still worth studying it as much as possible during the short time it's in our vicinity.
These interstellar objects are like free missions to the stars, where we can find out if the same processes that formed our solar system also happen throughout the Milky Way.
To get an even closer look, the European Space Agency is planning a Comet Interceptor mission in 2029 that will attempt to get up close to an as-of-yet unknown interstellar visitor that comes from a place far, far away and a time long ago.