American astronomers Juna Callmeier and Sean Raymond tried to answer this simple question. Their findings form the basis of an article published in the Royal Astronomical Society's Monthly Notices.
After calculating the tidal forces acting on a body moving in a closed orbit, the authors came to the conclusion that not every moon can be the central star for its own satellites.
“The planets revolve around the stars and the moons revolve around the planets, so it was natural to ask if smaller satellites could revolve around larger ones,” explains Raymond.
Their calculations show that only large moons in wide orbits around the host planets could be the centers of rotation of submoons. Tidal forces from both the planet and the moon work to destabilize the orbits of submoons orbiting smaller moons or moons that are closer to their host planet.
Theoretically, Callisto (the moon of Jupiter), Titan and Iapetus (Saturn) and the moon, which we know well, can have their own satellites in our solar system. But even in these cases, nothing similar to submoons has yet been found. This obviously means that the proposed mechanism needs to be clarified.
“The absence of submoons in our solar system, even orbiting moons that could theoretically have them, could give us a clue about how our and neighboring planets formed, about which there are still many questions,” explains Collmeier.
It is believed that the moons orbiting Saturn and Jupiter were born from the disk of gas and dust that surrounded the giant planets in their later stages of formation. On the other hand, our own moon is believed to have originated after a giant impact between a young Earth and a Mars-sized body. The lack of stable submoons could help scientists better understand the various forces that have shaped the moons we see.
Sergey Sysoev
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