Wonder Astronomers: Can Moons Have Moons?

Inquisitive kids ask some questions that parents just can not answer. Astronomer Juna Kollmeier's give it a real stumper one night back in 2014:

"Can moons have moons?"

So she went hunting for an answer.

As far as scientists can tell, none of the Solar System's planets have submoons, moons orbiting their moons. Kollmeier from the Observatories of the Carnegie Institution of Washington and astronomer Sean Raymond from the University of Bordeaux. But in the wake of an enormous exomoon possibly spotted around another star, the question is as prescient as ever-and-mighty important information about the history of our own Solar System.

"We're really just scratching the surface here," said Kollmeier told Gizmodo.

The team's short analysis of the world, perhaps 10 kilometers in radius, could only survive around large moons (such as the ones we see in our solar system) far away from the host planet, according to the paper published on the arXiv preprint server . Moons that are too close to their host or planets, or they are too close to their planet or planet, or shooting it out into space.

But even if the Solar System is not known, there are some moons that we could have had, based on their size, according to the analysis. That includes Earth's own Moon.

Though Kollmeier has thought about the issue since 2014, he has come to the fore. Scientists using Hubble recently observed something tantalizing: A few hours after the massive exoplanet Kepler-1625b passes in front of its star host, the star's light seems to dim a second time. Astronomers thought that a moon of the size of Neptune might be orbiting the 10-Jupiter-mass planet and causing the second dimming. Given the enormous size of this potential exomoon, it could be a good candidate for having a moon of its own: a submoon.

Astrophysicist Michele Bannister from Queen's University Belfast in Northern Ireland thought the question of whether or not her moon was intriguing. This article is not available in English, French, English, French, Spanish, French, English, French other small moons orbiting that point. Similarly, the 47171 Lempo system contains two minor planets orbited by a third, much smaller satellite.

Still, the paper has not been published yet, and there is work left to be done. Bannister would like to see more information on how to calculate the data and how to calculate it. had a companion of its own.

Kollmeier agreed that this is a preliminary work and these are important questions to ask. She said, "I'm just so excited that people are interested in this.