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 say new interstellar visitor 3I/ATLAS is 'very likely to be the oldest comet we have ever seen' Why scientists are so excited about the newfound interstellar comet 3I/ATLAS (op-ed) ...

The gases that may be seen in the future as 3I/ATLAS is heated by the sun will test our model," team member Michele Bannister, of the University of Canterbury in New Zealand, said.

Scientists believe Comet 3I/ATLAS may have originated from a rarely seen corner of the Milky Way over 7 billion years ago, before our solar system existed.

In other words, 3I/ATLAS may indicate that the Milky Way has been producing interstellar objects since close to its creation, some 13 billion years ago.