Interstellar comet 3I/ATLAS might be older than our Sun and is estimated to be between eight and 14 billion years old and this discovery has left scientists stunned. The third only known to enter our solar system, theories suggest that interstellar comet 3I/ATLAS could be alien too. Whether it is a 14-billion-year-old piece of cosmic history or a scout from another civilisation, 3I/ATLAS remains the most significant astronomical event of the decade.