Dr Sheppard said: 'This is an unstable situation.
Gareth Williams, an astronomer at the Harvard-Smithsonian Center for Astrophysics and director at the International Astronomical Union's Minor Planet Center, predicted that "there aren't any bigger objects undiscovered out there" around Jupiter.
Because Jupiter moves across the sky at a known speed, anything nearby moving at the same speed in the same direction becomes a candidate for a moon - but confirmation is a time-consuming process, Sheppard explained to ScienceAlert.
The team was using the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile, which recently got upgraded with the Dark Energy Camera. What makes it odd, however, is its maverick orbit: it is the only prograde Jovian satellite discovered to date to orbit at the same distances as the retrograde moons. This new moon, called Valetudo, is a bit of a renegade.
But that didn't necessarily suggest they were moons - they could have been asteroids orbiting the sun.
Valetudo orbits Jupiter in the same direction that the planet spins, but a bunch of other small moons share the same orbital path while travelling in the opposite direction.
Due to their sizes-one to three kilometers-these moons are more influenced by surrounding gas and dust.
USA claims all eligible migrant toddlers reunited with parents
Its explanation: "1 child can not be reunified at this time because the parent's location has been unknown for more than a year". Another 24 children were not returned because the parents are in criminal custody in the United States or have been deported .
The team discovered 12 new Jovian moons, ten of which were never-before-seen objects, while a further two had been spotted previously by scientists. The largest among them are the Galilean satellites-Io, Europa, Ganymede, and Callisto-large moons that orbit close to the planet.
The so-called "oddball" has such a unique orbit that it is at risk of smashing into the other moons - a cosmic collision that could risk wiping the space rocks out. The new moons were found in three distinct clusters and are thought to be debris left over when three larger bodies were broken apart in earlier collisions. This proved to be quite helpful, as the unknown moons around Jupiter are small and dim.
The team suspect the "oddball" is the last-remaining remnant of a once-larger prograde moon that formed some of the retrogrades during past head-on collisions.
Jupiter's moons are arranged in a specific pattern that the giant planet has worked out over time. The retrograde set of moons take about two years to complete a lap around Jupiter, and the prograde ones take under a year. Because of that small moon's orbit, it may be eventually be destined for an crash.
In the spring of 2017, Jupiter happened to be in an area of sky the team wanted to search for Planet Nine.
Scientists were looking for objects on the fringes of the solar system a year ago when they pointed their telescopes close to Jupiter's backyard, according to Scott Sheppard of the Carnegie Institute for Science in Washington. But Juno is too close to the huge planet and its field of view is too small to capture images of the planet, Sheppard said.
Of the 12 newly discovered moons, 11 are "normal, "according to a statement from the Carnegie Institution for Science". Their existence shows that they were likely formed after this gas and dust dissipated.