An old earth legend, Jason and The Argonauts, tells of a pair of deadly rocks that stood at the narrow passage between the Sea of Marmara and the Black Sea. They would clash together whenever any living thing tried to pass between them

This system is home to a pair of shepherd moons ( 1a and 1b) around Planet 1, a ringed high metal content world. Planet 1 is also a close binary pair with planet 2. The four bodies fit inside an area cleared between the asteroid belts of the main star and are all very close to each other and collide approximately every 8 days.

The shepherd moons from which the system derives its name have slightly eccentric orbits with orbital period of 0.2 days. The small difference in orbital periods and short duration means that the planets have a synodic period of approximately 8 days. The difference between the semi-major axis of the orbits is small enough that he planets should clash into each other every time they pass each other.

On the 31st August 3306, a team from Canonn Interstellar Research visited the system to observe the precise moment that the bodies would pass. The planets collided with an overlap of little under one radius while the orbit was observed to be at approximately half the furthest distance. As a result Canonn are predicting that the bodies should collide approximately every 8 days with some near misses.

The moons themselves are small radius landables under 300km in radius. In fact all 4 bodies are landable so it is possible to get ringside seats to watch the collision.