J1407b, has the largest ring system yet seen – around 200 times larger than Jupiter's (the largest in our solar system). Its host planet is likewise massive: we don't know whether it's a gas giant or a brown dwarf. So far, it's been classified as a super-Jupiter stellar body.
This is an updated (quotes and sources) version of the previous article.
If it resided in our solar system, the greatest planetary ring system we've discovered would dominate the sky.
To put this ring system into perspective, if Saturn possessed the same rings, they would be several times greater in diameter than the moon in the night sky. It would not only be visible with the naked eye, but it would completely dominate the view. Overall, the exoplanet has over 30 layers of rings.
“It’d be huge. You’d see the rings and the gaps in the rings quite easily from Earth,” said Matthew Kenworthy of the Leiden Observatory in the Netherlands, one of the co-authors on the paper describing the findings, at the time. “It’d be several times the size of the full moon.”
Maybe the size of its rings helped too because J1407b was the first confirmed case of an exoplanet with a ring system. So far, it’s also the only exoplanet with rings that we’ve spotted.
Still, in cosmological terms, such lush manes of rings do not last for long. Researchers expect them to get progressively thinner and disappear in the next several million years as new moons form from the sheer quantity of material zipping and zapping through J1407b’s rings. Compared to planets in our solar system, J1407b is also very young, at only about 16 million years old. The Sun and Earth are 4.5 billion years old.
So it might be just youthful energy that makes large ring systems possible. Right now, we simply don’t know. The methods we use to spot exoplanets (planets outside our solar system) aren’t very good at all at picking up ring systems — they can do it, but there’s a lot of luck involved.
For now, our best knowledge of planetary ring systems come from our neighboring planets. There may well be larger rings than those boasted by J1407b out there, but until we can get a better view into deep space — or, even better, make our way there — they will likely remain undiscovered.
Reference: Astrophysical Journal