Ploonets: Why Scientists Are Trying To Make It A Thing

Do you remember moonmoons?

Which is the name scientists gave for a moon’s satelite, or the moon of a moon.  If you do, then you know that scientists have a knack for pulling a curveball from time to time when it comes to naming a newly discovered cosmic object.

They did it for moonmoons, and now that they’ve done it again, for ploonets.

A hypothetical new class of cosmic object, ploonets, funny as they sound, are exactly what you think: kind of a mix between a moon and a planet. And according to scientists, their existence could be behind why we haven’t encountered any exomoons yet.

That is, according to a paper submitted to the Monthly Notices of the Royal Astronomical Society, which laid it all out: exomoons that are orbiting giant exoplanets in other planetary systems could be kicked out of orbit due to an exchange of angular momentum between the three space bodies, usually from stars, the planet and the moons themselves.

According to the study, the “regions” that surround stars are very extreme for exomoons, meaning that they can’t survive in the environment. As a result, they get pushed out of orbit, where they become protoplanets, or as the scientists like to call them, ploonets.

"If large exomoons form around migrating giant planets which are more stable (e.g., those in the Solar System), what happens to these moons after migration is still under intense research," said the reseachers in the paper. "This paper explores the scenario where large regular exomoons escape after tidal-interchange of angular momentum with its parent planet, becoming small planets by themselves. We name this hypothetical type of object a ploonet.”

According to the astronomers, the concept of evicted exomoons that became ploonets should be more common as it is, even though what we know about them are still largely hypothetical.

Still, the astronomers believe the hypothesis is incredible, and that there’s a possibility that our planet could be making a ploonet of its own right now.

"Earth's tidal strength is gradually pushing the Moon away from us at a rate of about 3 centimetres a year," Mario Sucerquia, one of the paper’s lead authors, said. "Therefore, the Moon is indeed a potential ploonet once it reaches an unstable orbit."

Moon The moon is pictured over the northern France city of Bailleul on February 25, 2019. The world’s first commercial lunar lander Beresheet suffered a major glitch that forced its computer to reset and cancel a planned maneuver on Feb 25, 2019. Philippe Huguen/AFP/Getty Images