Aegis

A hydrogen-helium gas giant, Aegis was the site of an unparalleled cosmic event roughly 1.8 million years ago. An extrasolar body about 200 square kilometers in size was drawn into Aegis' gravity well and struck the Jovian planet, blasting enough dust and material into orbit to create a ring.

An urban legend has grown over this event. The story goes that if the extrasolar body (usually called a comet) was unaffected by the gravity well of Aegis, it would have coincided with an orbit of Trident and created an extinction-level event on that planet. Prevailing scientific opinion holds that this is an exaggeration at best.