From Forbes:
A bizarre system "singing planets" has been unearthed by astronomers.
The stars system—known as TOI-178, and about 200 light-years from us—features six planets, five of which are locked in a highly unexpected "rhythmic dance" as they move in their orbits.
Described as in resonance, the five planets' orbits create patterns that repeat themselves, with some of them aligning every few orbits.
[…]
However, the planets orbiting the star TOI-178 are in a much more complex chain of resonance. They're locked in a 18:9:6:4:3 resonance—the longest yet discovered in a system of planets—a level of complexity that adds to their entrancing "song."
It was only after uncovering the "song" of star system TOI-178 that the astronomers found a sixth planet. They used the resonant rhythm to calculate where in its orbit an additional planet would be when they next had a window to observe the system—then successfully got data on it.
Pretty cool!
Listen To Six Alien Planets 'Singing' To Us In A Hypnotic Rhythm From 200 Light-Years Away [Jamie Carter / Forbes]