Astronomers first spotted this object in August, when it baffled them with its appearance as an unidentifiable blurry blob. So they did what anyone in a similar situation would do—recruited the Hubble telescope for help. Zoning in on the mystery object, they found that it was still baffling, as it appeared to be a comet on crack. P/2013 P5 projects gas and dust in all directions, like spinning fireworks or a bicycle wheel. During a two-week window in September, its appearance changed and it seemed to have turned around. The tail also looked like it changed in structure.
UCLA lead investigator David Jewitt says he and the other astronomers were “literally dumbfounded” by these observations. It’s possible that this is an asteroid that over time experienced uneven heating by the sun, which caused its rate of rotation to increase enough for it to emit gases and other materials—in other words, the asteroid may be shedding its own matter.
A recently published study describes how simulations run at Germany’s Max Planck Institute for Solar System Research lend credence to this idea. The results demonstrate how an asteroid whose rotation had been sped up by the sun could experience sudden dust ejection from the increasing centrifugal source, which would explain the multiple tails. Astronomers will continue to monitor the P/2013 P5, specifically to see if the dust jets are emanating from the asteroid’s equator, which would help confirm the theory. Right now scientists estimate that the object has lost 100-1,000 tons of dust, which is only a small percentage of its total mass—the thing is 240 meters wide.
Comets and asteroids are similar, but their composition is different. Asteroids are comprised of rock and metal, which is why some companies want to mine them. Comets have some rocky material too, and some dust, but they’re mostly made of ice. Asteroids tend to hang out closer to the sun, while comets start farther away from the sun, and, as they grow closer, their ice starts to vaporize, which is what gives a comet a tail. More rare than asteroids, comets also have much bigger orbits and don’t bunch together.
Whatever the P5 object is, it’s not just your garden-variety comet or asteroid or hybrid eclipse. While it probably isn’t unique in space, it’s strange enough to blow astronomers’ minds, which is something we can always count on from the cosmos.