A 'dirty snowball' melting in the sun should behave predictably, trailing gas and dust away from our star. But what happens when an object appears to be defying that fundamental law, shooting a plume towards the sun, and doing so with a rigidity that confounds every textbook explanation?
That is the question currently vexing the world's leading astrophysicists as they observe 3I/ATLAS, an interstellar comet that is now rewriting the rules of cometary physics — or perhaps, according to some controversial voices, demonstrating the principles of alien engineering. This cosmic interloper, only the third confirmed visitor from another star system after 'Oumuamua and 2I/Borisov, is behaving in an unprecedented manner, leading to an extraordinary split in the scientific community.
