Neptune Moon Dance (animation)
The Voyager 2 spacecraft discovered Neptune moons Naiad and Thalassa in 1989.
The moonlets are only about 60 miles (100 km) wide.
If we race along with Thalassa around Neptune, Naiad appears to be moving in a wave-like pattern.
That's because, compared to Thalassa, Naiad's orbit is tilted by about five degrees.
It takes about seven hours to complete the orbits
Naiad spends half of each orbit above Thalassa and half below.
If we plot multiple orbits, we see Naiad in a constant dance with Thalassa.
This is called a resonance.