At the end of last year, astronomers decided that the moons that orbit other moons should have their own special name. The "moon-moon" label was offered, and quickly ridiculed for how silly it sounds, but the name seems to have stuck, for better or for worse. With that problem solved, some have turned their attention to another type of world that does not have a specific name.
Moons that escape the gravity of their host planet and go solo can be called many things, and their label often depends on how big they are. For the particularly massive moons that are released, the researchers have a new name: Ploonets.
In a new article published in Terrestrial and planetary astrophysics, researchers propose the name "ploonet" to describe a large moon that falls apart.
"This paper explores the scenario in which large regular exomoons escape after the tidal exchange of angular momentum with their parent planet, becoming small planets by themselves," the team writes. "We call this type of hypothetical object a ploonet."
The researchers suggest that this type of world may be the result of large exoplanets of "hot Jupiter" migrating to their host star. Inspections of exoplanets have detected several planets of this type, and it is believed that they probably formed at a greater distance from their respective stars and then slowly slid inward.
When that happens, it is possible that the change in gravitational forces causes the large moons to be released from their existing orbits and become independent worlds by themselves. The computer simulations showed that this could happen, and in those cases, the researchers believe that we should call them ploonets.
Surprisingly, our own Moon could one day become a ploonet. The Moon is slowly moving away from Earth at a very slow pace, and it is possible that it will eventually enter a much less stable orbit and even go solo. Future generations could see the birth of a ploonet happening before their very eyes.