Though NASA has confirmed 3,440 planets outside our solar system, no one has ever been able to confirm an exomoon. While we know they’re out there, huddling around their respective planets, new research could clue us into why we haven’t been able to find one yet—and it could be because their planets are assholes.
A team of researchers at Nanjing University in China have been running simulations of exoplanets, their stars, and their theoretical moons, based on exoplanets scientists have already confirmed. These exoplanets tend to orbit their stars very closely—much closer than Earth orbits our own Sun.
In the simulations, the team gave each exoplanet 500 moons. The group found that over time, photo evaporation from high energy photons—caused by the exoplanet orbiting the host star so closely—forced the exoplanets to lose some of their atmospheric mass. As a result, the exoplanets also lost some of their gravitational pull, causing their exomoons to enter an elliptical, unstable orbit that ultimately allowed them to escape the orbit altogether. By the end of each simulation, very few moons—if any—remained. The team’s findings were published on December 1st, 2016 in The Astrophysical Journal.
The researchers found that once exomoons were kicked out of their planets’ friendzones, their fates varied. Some became rogue planets, wandering the galaxy alone, unattached to any star. Some of the other moons that remained in orbit ended up colliding with their host planets.
Hopefully, the study will serve as a polite warning to those searching for exomoons: Don’t look at planets that orbit too close to their suns. They’re jerks.