The mysterious asteroid is accelerating, and scientists don't know why.
Most asteroids behave in a very predictable way: they are pushed and pulled by external forces - gravity and the pressure of sunlight. But the same cannot be said for celestial body 1998 KY26. This stone rushes down the track with an acceleration unmatched by any of the normal models.
This stone acts as if there is an engine hidden inside it. The asteroid rotates around its axis at high speed - it makes a full rotation in only five and a half minutes. And its orbit shows an additional acceleration directed perpendicular to the plane of the orbit. Scientists have suggested that it may be a "dark comet".