Cupid and Belinda, doomed moons of Uranus

Uranus with its vertical ring system.

A pair of star-cross'd lovers orbits Uranus, and when they rush to meet their fate, the duo could leave the cosmic stage littered with more bodies than the final scene of Hamlet.

But the deaths of the moons Cupid and Belinda might not bring down the curtain on Uranus's satellites. 

Instead they could mark the beginning of a cycle between moons and rings that has been the central drama of the Uranian system for hundreds of thousands of years.

Named mostly after characters in Shakespeare plays, Uranus's inner moons are a tight and mysterious group. 

They orbit closer to the planet and each other than any other set of satellites in the solar system, packing 13 moons into the space of 10,000 kilometres.

Earlier work from 1997 suggested the inner moons would bump into each other, and often. Since then, three new inner moons – Perdita, Cupid and Mab – have been discovered in archival data from Voyager 2 and new images from the Hubble Space Telescope.

Robert French and Mark Showalter of the SETI Institute decided to run orbital simulations to see if the new moons were also in danger.

The result: "Something bad always happened," French says. "Almost no matter what assumptions we make, Cupid is going to die."

The authors think Cupid and Belinda are more likely to break apart than stick together. However, even that scenario leads to multiple collisions, which could solve another of the planet's mysteries.

Material close to a planet tends to get pulled apart into rings, while debris that's sufficiently far away can clump together to form moons. 

In addition to a traditional set of rings and moons, Uranus has a small, faint ring in an anomalous place, just inside the orbit of Cupid. That moon, meanwhile, has such a short life expectancy that French is surprised it exists.

"So we have this ring that shouldn't be there because it should be a moon, and a moon that shouldn't be there because it should smack into something and create a ring," he says. "Perhaps there is a cycle going on."

French suggests that the inner moons and rings are constantly recycling in a process similar to what's happening in Saturn's F ring. "Maybe this isn't the end of Cupid's life," he says. "Maybe it's the middle or the beginning, and it's just not going to last very long."