By Samuel Lopez | USA Herald The countdown to December 19, 2025, has begun—a date that could forever redefine humanity’s understanding of its place in the cosmos. That’s when interstellar object 3I/ATLAS will make its closest approach to Earth, offering scientists their clearest opportunity yet to determine whether this mysterious traveler is a natural comet On December 19, 2025, the interstellar object 3I/ATLAS will make its closest approach to Earth—offering scientists a historic opportunity to determine whether it’s a natural comet or an artificial probe.