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.

When the news started to spread on July 1, 2025, about a new object that was spotted from outside our solar system, only the third of its kind ever known, astronomers at Michigan State University—along with a team of international researchers—turned their telescopes to capture data on the new celestial sighting.

A week and a half after its discovery, there are clues about the origin and age of the interstellar comet 3I/ATLAS – and predictions about its composition.