A mystery interstellar object discovered last week is likely to be the oldest comet ever seen—possibly predating our solar system by more than 3 billion years, researchers say.

I/ATLAS isn't just fascinating because it is the third interstellar visitor found in the solar system; new research suggests it's also the oldest comet ever seen, at over 7 billion years old.

A mystery interstellar object spotted last week by astronomers could be the oldest comet ever seen, according to scientists. Named 3I/Atlas, it may be three billion years older than our own solar system, suggests the team from Oxford university.