Astronomers have discovered 3I/ATLAS, the third interstellar object ever observed, traveling on an unusual trajectory. Harvard astronomer Avi Loeb suggests it could be billions of years old and even speculates it might be an extraterrestrial probe, a theory that has sparked controversy. Loeb initially estimated its size at 12.4 miles, much larger than the previous interstellar object, 'Oumuamua, leading to questions. While further observations suggest it's not a comet, Loeb's 'by design' hypothesis remains a possibility, pending further data as the object approaches the sun.

Prepared by Olivia Bennett and reviewed by editorial team.