It’s a question you might have asked yourself while looking at the night sky: Could the Earth support more moons like the Moon? Or would the gravitational forces involved pull our planet off its safe course?
The answer, according to a new study, is that Earth could support two more moons the size of the Moon, and even more if they were smaller. This is based on detailed physical simulations covering a period of 3,000 years.
It’s an interesting hypothesis to explore, but the research also has a practical purpose: it could help astronomers understand how Earth formed and find other Earth-like planets (and their moons) in the world. universe at large.
“Based on this work, the dynamical stability of lunar systems limits the existence of exomoons for Earth analogues in their respective habitable zones, where confirmation of future observations is needed,” the researchers write in their published article.
The simulations performed by the team were limited by the distances between the hypothetical moons and Earth, and between the moons themselves. Careful balancing is needed to prevent a moon from drifting through space or crashing into the planet it orbits.
Three different moon sizes were also analyzed: one with the mass of our Moon, one with the mass of Pluto (about one-sixth the size of the Moon), and one with the mass of the dwarf planet. Ceres (about one hundredth the size of the Moon).
Based on the simulations, Earth can support up to three moons the size of our current Moon, up to four moons the size of Pluto, and up to seven moons the size of Ceres – assuming they are all the same size, which they probably would be. not to be.
“Not all moons of Jupiter and Saturn are the same size, so we might expect multiple moons to be different sizes, and to get the absolute answer we would need to include that,” said physicist Suman Satyal of the University of Texas at Arlington says new scientist.
Jupiter and Saturn each have dozens of moons while Mercury and Venus have none, which scientists say is likely due to the different ways these planets formed and their different positions in the solar system.
Earth and Earth-like worlds elsewhere in the Universe could potentially support more than seven moons if they were of varying sizes, the researchers say. This, however, is beyond the scope of the current study, as is the gravitational pull of the planets.
“Our model ignores the gravitational effects of all other planets in the solar system,” said Billy Quarles, physicist from the University of Texas at Arlington.
“This is important when we look beyond the solar system, because there are a large number of systems with a single candidate planet. There are currently two exomoon candidates, but they both orbit Jupiter-like planets about a astronomical unit”, which is about 150 million kilometers (93 million miles).
Additional moons around Earth would certainly have made the night sky more interesting. They would have to orbit at different distances from Earth for this to work, in which case they would appear in the sky as having a different size – and would also be in different phases (such as full or crescent).
“Many movies illustrate the possibility of exomoons, like Pandora from Avatar, or the forest moon Endor from Star Wars,” said Skittles.
“Our study could help future work appear more astronomically accurate.”
The research was published in the Royal Astronomical Society Monthly Notices.