Uranus' Moons Are Unluckier Than We Thought

By Rae Paoletta on at

Uranus can’t seem to catch a break these days. Besides spinning on its side like the drunkard of the solar system and being the butt of everyone’s jokes, new research suggests its several of tiny moons will collide in a million years.

According to research submitted recently to ArXiv by a team of astronomers, one of Uranus’s moons—Cressida—will likely instigate the smackdown. The researchers figured this out by first deducing Cressida’s mass, which they were able to do by studying its relationship with one of Uranus’s rings using occultation data collected from Earth-based observations and Voyager 2. Cressida’s gravity makes this ring—called Eta—slightly triangular, which is very unusual yet totally on brand for Uranus. Apparently, Cressida is pretty light—only about 1/300,000 the mass of our Moon. According to the researchers, this marks “the first direct measurement of an inner Uranian satellite’s mass.”

The researchers used Cressida’s mass and orbit to determine its possible doom. Since Uranus’ 27 moons are tightly packed together, the team posits that in a million years, Cressida will likely have a deadly encounter with one of its neighboring moons, called Desdemona. Previous research and simulations suggest Cupid and Belinda will also probably smack into each other some time between 1,000 and 10 million years from now.

Uranus’ moons have traditionally been difficult to spot, since, aside from being very small and very fair away, they’re covered in a mysterious dark material. Its largest moons—Oberon and Titania—were first spotted by British astronomer William Herschel back in 1787. In 1986, the Voyager 2 spacecraft hit the jackpot while studying Uranus and discovered 10 other moons, including Desdemona and Cressida. Since then, Hubble observations have helped bring that number up to 27—for now.

In a million years, we’ll all be dead. But Uranus will still be stumbling on in the void, watching its moons crash into each other, just like that terrible Dave Matthews song. It’s poetry. [New Scientist, ArXiv]

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