The latest discovery of a dozen small moons brings the total to 79, the most of any planet in our solar system.
Gareth Williams at the International Astronomical Union's Minor Planet Center used the team's observations to calculate orbits for the newly found moons.
They quickly hit the jackpot - 12 new moons appeared in the images.
Also, if the moons had formed earlier, there likely would have been more crashes, the team explained.
Astronomers describe the twelfth new Jovian moon as an "oddball".
The discovery means Jupiter, the oldest and largest planet in the solar system, has more moons than any of the other seven. He and his team have been photographing the skies with some of today's best telescope technology, hoping to catch sight of this mysterious ninth planet.More news: 'Bohemian Rhapsody': Mercury becomes a legend in new trailer
Rather than delay their work, the researchers chose to pivot to studying moons of Jupiter which had flown into their gaze.
"This is an unstable situation", said Sheppard.
More than 400 years later, astronomers are still finding moons orbiting the solar system's largest planet.
They take about two years to orbit Jupiter. Jupiter is not in the frame, but off to the upper left.
Researchers would like to get a close-up look at the moons. Not yet, anyway. "Right now the only definition of a moon is something that orbits the planet", Sheppard said, as long as it isn't human-made.
"Valetudo's going down the highway the wrong way, so it's very likely it will collide with these other objects". There are also small interior moons that orbit in the same direction as Jupiter, which are referred to as prograde moons.More news: Trump Reverses Summit Remarks, Saying Russia Meddled in Election
Astronomers think retrograde moons have a different origin story from prograde moons, which travel in the same direction that their planet rotates.
The moons are small, ranging from just one kilometre to three kilometres in width. It has a prograde orbit at a distance where the rest of Jupiter's moons have retrograde orbits.
Jupiter, the fifth planet from the Sun, has a diameter of 142,984km.
According to the team, these moons, and especially Valetudo, likely did not form at the same time as Jupiter, but rather are probably the tiny remnants of larger objects that suffered numerous collisions as they circled the gas giant. As such, the orbit crosses those of the outer retrograde moons, raising the possibility of a possible head-on collision at some point in the future.
"Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System", Sheppard said in a statement. The planet must have acted like a vacuum, sucking up all the material that was around it.
"What astonishes me about these moons is that they're the remnants of what the planet formed from", he said. Understanding that smaller moons still exist in the outer regions of Jupiter's orbital regions suggests to astronomers that they formed after the planets.More news: Donald Trump Tweets Walk-Back After Playing Vladimir Putin Lapdog in Helsinki