The research, which can be read on the arXiv repository, notes that the two celestial satellites are only separated by approximately 1,150 miles, but they never get within 2,200 miles of one another, orbiting at slightly different speeds. Naiad also moves in a "zigzag pattern," whereas Thalassa does not.
"We refer to this repeating pattern as a resonance," said the study's lead author, Marina Brozovic, an expert in solar system dynamics at NASA's Jet Propulsion Laboratory, in a statement. "There are many different types of 'dances' that planets, moons and asteroids can follow, but this one has never been seen before."
The pattern never changes, as Naiad takes around seven hours to orbit the icy giant planet and Thalassa takes approximately seven and a half hours.
It's unclear how this pattern started, but Brozovic believes it may have occurred when their original pattern was disrupted after Neptune captured its largest moon, Triton, eons ago.
"We suspect that Naiad was kicked into its tilted orbit by an earlier interaction with one of Neptune's other inner moons," Brozovic added in the statement. "Only later, after its orbital tilt was established, could Naiad settle into this unusual resonance with Thalassa."
In April, a NASA scientist and his team at the Goddard Space Flight Center in Greenbelt, Md. said they were dreaming up new instruments that could potentially explore the atmosphere of both planets, utilizing advancements in technology over the past 30 years.
In March, scientists at NASA JPL proposed a mission that would explore Neptune's largest moon, Triton, which some have theorized could have an ocean hiding underneath its surface.