A leading US astrophysicist has warned that an alien attack could be imminent, claiming a mysterious object hurtling through our solar system may be an extra-terrestrial spacecraft.

Professor Avi Loeb of Harvard University believes the vast interstellar mass, known as 3I/ATLAS, might not be a comet at all — but a craft sent by an advanced civilisation.

The object, first detected on July 1, is around the size of Manhattan and weighs an estimated 33 billion tonnes, travelling almost twice as fast as previous interstellar visitors. Most scientists believe it’s simply a comet — but Prof Loeb doesn't believe the evidence adds up.

He warned: "It may come to save us or destroy us. If you want to take a vacation, take it before that date. Because who knows what will happen.”

He believes 3I/ATL

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