Sometimes astronomers find something that completely changes the way we think about planets, like a planet that is completely dwarfed by its ring system.
We aren’t totally sure why planets have rings. One theory is that rings form when a planet’s gravity is too strong to allow the debris that surrounds it to coalesce into a moon. Another theory is that passing asteroids or comets break apart nascent moons, turning them into rings. In any case, ring systems are governed by forces that keep the rings in check, whether they are thin like the ones around Jupiter or majestic like the system around Saturn where shepherd moons help keep each ring distinct from its neighbor.
The exoplanet called J1407b was discovered by a team of astronomers from the Leiden Observatory and the University of Rochester in 2012. And it has a massive ring system unlike any we’ve ever seen. The team modeled it indirectly. By measuring the variation in the dimming light as the planet passed in front of its host star, the astronomers could paint a rough picture of the system around the distant planet, which is far larger than either Jupiter or Saturn.
This planet’s system consists of more than 30 rings, each of which is tens of millions of miles across. Saturn’s rings, for a point of comparison, are only about 175,000 miles across. And this exoplanet’s ring system has gaps, which suggest that there might be moons within the rings similar to the shepherd moons Saturn has.
Leiden astronomer Matthew Kenworthy put it into an interesting perspective: “If we could replace Saturn’s rings with the rings around J1407b, they would be easily visible at night and be many times larger than the full moon.”
Discoveries like this one are as close as we can get to observing early satellite formation and help us understand how our own solar system formed. They also remind us that not everything is going to look familiar, because there’s a lot of variety in the universe.
IMAGE: Ron Miller/Rochester