- Unlikely size: over a million times more massive than 1I/‘Oumuamua.

- Unlikely trajectory: retrograde orbit aligned within 5° of the ecliptic plane.

- Combined probability of natural origin: ~1 in 100 million.

Means:

Thrusters (chemical or ion) could explain jets with far less mass loss, consistent with observed acceleration.

(http://www.autoadmit.com/thread.php?thread_id=5795738&forum_id=2)#49417549)