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 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.

Astronomers have spotted a new interstellar object — the third of its kind ever seen — shooting towards us through the solar system. Here's everything you need to know about 3I/ATLAS.