Elusive Planet Nine could be surrounded by hot moons

The elusive “Planet Nine,” which may or may not lurk in the outer reaches of the solar system, could be surrounded by a small swarm of potential moons, a new study reveals. What’s more, these moons could be the key to finding the missing planet.

Planet Nine, if it exists, lurks beyond the orbit of Neptune in an icy region known as the Kuiper Belt.

Scientists first proposed the existence of Planet Nine in a 2016 study in The Astronomical Journal

They used the hypothetical planet as a possible explanation for the unusual orbits of several extreme trans-Neptunian objects (ETNOs) — asteroids, comets, moons or dwarf planets that are beyond 30 astronomical units from the sun. (One astronomical unit is the distance between Earth and the sun.)

Researchers think the trajectory of these ETNOs can be best explained by the gravitational force of an undiscovered mass. Based on these orbits, Planet Nine is likely between five and 10 times larger than Earth and orbits the sun from around 250 times farther away than our planet does. There have even been suggestions that the elusive object could be a mini black hole.

So far, scientists searching in the area haven’t found any light signatures from Planet Nine. But that’s not surprising; the planet is too far away to be properly illuminated by the sun, so the only way to spot it would be if it eclipsed a distant light source, such as a galaxy or star within the Milky Way.