Artist's conception of the extrasolar ring system circling the young giant planet or brown dwarf J1407b is shown. The rings are shown eclipsing the young sun-like star J1407, as they would have appeared in early 2007. The best fit model is consistent with a system of at least 30 rings, and there are gaps where satellites ("exomoons") may have already formed. (Ron Miller)

When J1407 was discovered in 2012, it seemed like a  fairly run-of-the-mill star. But the researchers who spotted it saw signs of a strange eclipse -- a period when the star had dimmed and re-brightened. These sudden, drastic brightness changes went on for two months.

According to analysis published in Astrophysical Journal, a ringed planet like Saturn is in the star's system. But unlike Saturn, this ringed planet is a real bruiser. Its rings are massive and opaque enough to occasionally block out the star's light.

"This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn's rings are today," co-author Eric Mamajek, professor of physics and astronomy at the University of Rochester, said in a statement. "You could think of it as kind of a super Saturn."

This animation shows the large exorings around sun-like star J1407, which are markedly larger and heavier than Saturn's. (Matthew Kenworthy, Eric Mamajek/Leiden Observatory and University of Rochester)

If the rings around Saturn were replaced with this new "super Saturn's" rings, they'd be easily visible from Earth and much larger than the moon. The dust particles within it probably have as much mass put together as the Earth itself.

There are over 30 rings making up the structure. The researchers can tell because the star came in and out of its eclipse quite rapidly -- sometimes going light or dark over the course of just a few minutes -- indicating an intricate network of rings of different sizes with gaps in density in-between. At least one large gap is clearly defined, probably because a satellite formed out of the ring material and is now orbiting the planet along that path. If that's the case, the rings will probably continue to thin out over the next several million years as more moons form.

It's exciting to find a ringed planet outside our own solar system for the first time, especially since we're still not exactly sure when or how Saturn's rings, which are made mostly of ice with some traces of rock, formed.

"The planetary science community has theorized for decades that planets like Jupiter and Saturn would have had, at an early stage, disks around them that then led to the formation of satellites," Mamajek said. "However, until we discovered this object in 2012, no-one had seen such a ring system. This is the first snapshot of satellite formation on million-kilometer scales around a substellar object."


The rings around J1407b are so large that if they were put around Saturn, we could see the rings at dusk with our own eyes. (Credit: M. Kenworthy/Leiden)