NASA's Hubble Space Telescope observed that Comet 41P's speed slowed down significantly, it ceased its rotation, and then began rotating in the opposite direction.
This is remarkable, as it marks the first time astronomers have observed a comet changing its rotation direction.
This small comet, belonging to the Jupiter family, orbits the Sun approximately once every 5.4 years and is about 0.7 miles or one kilometer wide.
Scientists monitored this behavior using Hubble images, previous measurements from NASA's Swift Observatory, as well as data from the Lowell Observatory's Discovery Telescope.
In March 2017, that comet rotated once every 24 hours; but by May, its rotational speed had slowed down significantly overall.
Further data suggested that the nucleus probably stopped spinning in June 2017, then resumed in the opposite direction as the outflow of gases continued and the motion was rebuilt forward.
By December 2017, that comet began rotating very rapidly once again; after the change in direction occurred, it completed a full rotation in just about 14 hours.
Researchers say that uneven flows of gas and dust acted like small thrusters, dramatically altering the comet's rotational speed and direction.
Because Comet 41P is tiny, the forces from its gas emissions can drastically alter its rotation and, over time, destabilize it.
Scientists warn that continuous changes in rotation and activity could eventually cause a comet to disintegrate, thereby making it evident just how fragile such celestial objects are.