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.

Astronomers tracking an interstellar object flying through the solar system think it comes from a star at least 8 billion years old, almost twice the age of our sun