Rings Like Saturn’s, but Supersized

2 minute read

When the University of Rochester’s Eric Mamajek tells other astronomers about the object he and his colleagues discovered about 430 light-years from Earth, they tend to be skeptical—very skeptical. And no wonder: What he’s found is a giant ring system, sort of like Saturn’s, but some 200 times bigger, circling what may be an exoplanet between ten and 40 times the size of Jupiter. If you put these rings in our own Solar System, they’d stretch all the way from the Earth to the Sun, a distance of 93 million miles (150 km). And what’s more, there’s evidence that the rings are sculpted by at least one exomoon—something that also happens at Saturn, but not remotely on this scale.

MORE These ‘Vintage’ NASA Posters Imagine Travel Beyond the Stars

“It took us a year even to convince ourselves of what we were seeing,” says Mamajek, whose paper is based on a new analysis of observations taken back in 2007 by the SuperWASP planet search project. At the time, the observations seemed to make no sense: when a planet passes in front of a star, you usually see a dip in starlight that lasts for up to a few hours. In this case, the starlight dimmed for two months.

It wasn’t a steady dip, either. The star would fade, then brighten, then fade again, in a way that made no sense at all. When Mamajek and his group stumbled on the data in 2010, he says, “I took a printout of the light curve, put it on the wall, and stared at it for a week.” Crazy as it seemed, the most plausible explanation was a giant ring system with gaps like Saturn’s that let more or less light through at different times during the passage. “It’s the same indirect way the rings of Uranus were discovered in 1977,” he says.

See the Most Beautiful Space Photos of 2014

NASA's Nuclear Spectroscopic Telescope Array's first picture of the sun taken in high-energy X-rays released on Dec. 22, 2014.
NASA's Nuclear Spectroscopic Telescope Array's first picture of the sun taken in high-energy X-rays released on Dec. 22, 2014. JPL-Caltech/GSFC/NASA
An infrared image of a small portion of the Monkey Head Nebula (also known as NGC 2174 and Sharpless Sh2-252) captured by the Hubble telescope, released on March 17, 2014. The nebula is a star-forming region that hosts dusky dust clouds silhouetted against glowing gas.NASA/ESA/Hubble Heritage Team (STScI/AURA)
An infrared image of a small portion of the Monkey Head Nebula captured by the Hubble telescope released on March 17, 2014. NASA/ESA/Hubble Heritage Team
A spiral galaxy, also known as M106, about 23 million light years from Earth.
NGC 4258 is a spiral galaxy well known to astronomers for having two so-called anomalous arms that glow in X-ray, optical and radio light. Chandra X-ray Observatory/CXC/Caltech/NASA
https://www.flickr.com/photos/nasamarshall/15050207206/Eta Carinae: Our Neighboring Superstars (NASA, Chandra, 08/26/14)Eta Carinae is one of the most luminous known star systems in our galaxy. It radiates energy at a rate that is 5 million times that of the Sun. Most of this energy is radiated at infrared wavelengths. It is shrouded in a rapidly expanding cloud of dust which absorbs radiation from the central star and re-radiates it in the infrared.
Eta Carinae is one of the most luminous known star systems in our galaxy seen here in this photo released on Aug. 26, 2014.JPL-Caltech/NASA
A reprocessed picture shows off the amazing colors of Europa, a mysterious ice-covered moon of Jupiter, as they have never been seen before released on Nov. 21, 2014.
A reprocessed picture shows off the amazing colors of Europa, a mysterious ice-covered moon of Jupiter, as they have never been seen before released on Nov. 21, 2014.NASA/JPL-Caltech/SETI Institute
Reid Wiseman ‏@astro_reid Jun 1A simple toy from my childhood makes for a cool picture in space. pic.twitter.com/yddfNTwiow
Astronaut Reid Wiseman tweeted this photo on June 1, 2014 from the International Space Station "A simple toy from my childhood makes for a cool picture in space."Reid Wiseman—NASA
Infrared Image of Saturn's Rings
This image of Saturn's rings was taken by a camera on the Cassini spacecraft released on Jan. 21, 2014. JPL-Caltech/NASA/EPA
ESA's Optical Ground Station in Tenerife
A long exposure of the European Space Agency's Optical Ground Station at the La Teide Observatory on the Canary Islands, Spain released on April 27, 2014.EPA
An aurora near Australia seen from the International SPace Station, released on July 15, 2014.
An aurora near Australia seen from the International Space Station released on July 15, 2014.NASA
NASA: LL Ori and the Orion Nebula
This close-up of cosmic clouds and stellar winds features LL Orionis interacting with the Orion Nebula flow. NASA/Sipa
The Eagle Nebula, also known as as Messier 16 or M16, and the 'Pillars of Creation' in the constellation Serpens in May 2014.
The Eagle Nebula also known as as Messier 16 or M16, and the 'Pillars of Creation' in the constellation Serpens in May 2014.Adam Block—Mount Lemmon Skycenter
Russell Crater dunes on Mars released on Feb. 5, 2014.
The Russell Crater dunes seen on Mars in this photo released on Feb. 5, 2014.JPL/University of Arizona/NASA
NASA image of Saturn taken with the Cassini spacecraft wide-angle camera
Saturn taken with the Cassini spacecraft wide-angle camera on Nov. 23, 2013 and released for the first time on Feb. 3, 2014. NASA/JPL/Caltech/Reuters
This vista of the Endeavour Crater rim taken by Opportunity Rover combines several exposures taken by the rover's panoramic camera (Pancam) on the 3,637th Martian day, or sol, of the mission on April 18, 2014 and was released on May 19, 2014.
This vista of the Endeavour Crater rim taken by Opportunity Rover combines several exposures taken by the rover's panoramic camera on April 18, 2014 and was released on May 19, 2014.JPL-Caltech/Cornell University/NASA
Alexander Gerst ‏@Astro_Alex Jul 6 View translationHarsh land. Windswept valleys in northern #Africa / Hartes Land. Windgefraeste Taeler in Nordafrika pic.twitter.com/sFcbhRIF2Z
Astronaut Alexander Gerst ‏tweeted this photo on July 6, 2014 from the International Space Station "Harsh land. Windswept valleys in northern #Africa / Hartes Land"Alexander Gerst—NASA
The moon over northeast Greenland in March 2014.
The moon over northeast Greenland in March 2014.Michael Studinger—NASA
NASA picture of a crescent moon rising over the cusp of the Earth's atmosphere
A crescent moon rises over the cusp of the Earth's atmosphere in this picture by Japan Aerospace Exploration Agency astronaut Koichi Wakata onboard the International Space Station on Feb. 1, 2014.NASA/Reuters
An optical image, from the Digitized Sky Survey of the Flame Nebula released on May 7, 2014.
An optical image, from the Digitized Sky Survey of the Flame Nebula released on May 7, 2014. DDS/NASA
New Hubble infrared view of the Tarantula Nebula
New Hubble infrared view of the Tarantula Nebula released on Jan. 9, 2014. NASA, ESA, E. Sabbi (STScI)—NASA, ESA, E. Sabbi (STScI)
The sun emitted a significant solar flare, peaking at 7:28 p.m. EST on Dec. 19, 2014. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. This flare is classified as an X1.8-class flare. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc.
The sun emits a significant solar flare on Dec. 19, 2014 as seen from NASA’s Solar Dynamics Observatory, SDO/NASA
Astronaut Reid Wiseman tweeted on July 3, 2014 "Hurricane #Arthur has grown an eye since we last met."
Astronaut Reid Wiseman tweeted this photo from the International Space Station on July 3, 2014 "Hurricane #Arthur has grown an eye since we last met." Reid Wiseman—NASA
The Elephant's Trunk Nebula, also known as IC 1396, on April 14, 2014.
The Elephant's Trunk Nebula, also known as IC 1396 on April 14, 2014.Eric Coles
As an island in the moist, atmospherically turbulent North Atlantic, Iceland is often shrouded in cloud cover and hard to observe from space. And lately, the island is making some of its own cloud cover, as the Earth has split open between the Bardarbunga and Askja volcanoes and spewed lava and hot gas. The view of the Holuhraun lava field has been spectacular from the ground and from low-flying aircraft. Infrared imaging makes the view spectacular from space, too.On September 6, 2014, the Operational Land Imager (OLI) on Landsat 8 captured this view of the ongoing eruption. The false-color images combine shortwave infrared, near infrared, and green light (OLI bands 6-5-3). Ice and the plume of steam and sulfur dioxide appear cyan and bright blue, while liquid water is navy blue. Bare or rocky ground around the Holuhraun lava field appears in shades of green or brown in this band combination. Fresh lava is bright orange and red. (Download this large image to see the same area in natural color.)“Thermal imagery can be used to determine the extent of the lava flows and the heat loss,” noted Ashley Davies, a Jet Propulsion Laboratory scientist and leader of NASA’s Volcano Sensor Web team. Infrared imagery can help scientists estimate the effusion rate—the rate at which lava is pouring out of the Earth—as well as the sulfur dioxide content of the plume. “And high resolution imagery of this kind allows us to model the dynamics of the emplacement process. In this case, individual vents can be seen feeding separate lava flows that combine into a main channel feeding an expanding lava flow field.”By some accounts, Holuhraun has spewed more lava this month than any Icelandic volcano since the 19th century. As of September 9, 2014, the new lava flow was 16 kilometers (10 miles) long and covered about 20 square kilometers (8 square miles), according to the University of Iceland.The plume from Holuhraun is rich with sulfur dioxide (SO2), a rotten-smelling gas
The Holuhraun lava field as seen with infrared imaging captured by the Operational Land Imager on Sept. 6, 2014, NASA
INDIA-SPACE-SCIENCE-MARS
Mars is seen in an image taken by the ISRO Mars Orbiter Mission (MOM) spacecraft released on Sept. 30, 2014.ISRO/AFP/Getty Images
APTOPIX Kazakhstan Russia Space Station
The Russian Soyuz-FG rocket booster with Soyuz TMA-13M space ship carrying the Expedition 40 crew to the International Space Station launches from the Russian leased Baikonur cosmodrome, Kazakhstan on May 29, 2014.Dmitry Lovetsky—AP
Using the CIVA camera on Rosetta’s Philae lander the spacecraft snapped a ‘selfie’ with a comet passing by in the background in this photo released on Oct. 14, 2014.
Using the CIVA camera on Rosetta’s Philae lander the spacecraft snapped a ‘selfie’ with a passing comet in this photo released on Oct. 14, 2014.Rosetta/Philae/CIVA/ESA
Saturn, which appears as a thin crescent, broken only by the shadows of its rings, was captured by the Cassini spacecraft cameras in this image released on March 17, 2014. This view looks toward the unilluminated side of the rings from about 42 degrees below the ringplane.
Saturn was captured by the Cassini spacecraft cameras in this image released on March 17, 2014. JPL-Caltech/NASA
Handout of the evolving universe is shown in this composite of separate exposures taken in 2003 to 2012 with Hubble's Advanced Camera for Surveys and Wide Field Camera 3
A composite of separate exposures taken in 2003 to 2012 with Hubble's Advanced Camera for Surveys and Wide Field Camera 3 of the evolving universe is shown in this image released on June 3, 2014.NASA/Reuters
Reid Wiseman ‏@astro_reid Jul 1Here is a #TodaySunrise from space for @MLauer pic.twitter.com/xyckQ0AAdVHere is a #TodaySunrise from space for @MLauer." - Reid Wiseman via Twitter on July 1, 2014.
Astronaut Reid Wiseman tweeted this photo from the International Space Station on July 1, 2014 "Here is a #TodaySunrise from space for @MLauer"Reid Wiseman—NASA

The planet itself doesn’t show up in the observations, but that could be explained if the ring system is slightly off-center as it moves in front of the star. You can see how this works in an animation put together by Mamajek’s collaborator Matthew Kenworthy, of the University of Leiden, in the Netherlands.

The star which the new planet orbits is thought to be very young—about 16 million years, compared with our own Solar System’s 4.6 billion. If the scientists are right about what they’re seeing, the mammoth ring system will get smaller over time as the outer bands condense into moons. “That’s what you see in [our] Solar System,” says Kenworthy. “You have rings tucked in close to the planets and moons further out. So presumably we’re seeing the intermediate step.”

It all seems familiar, except for the ring system’s size, which is unprecedented—and which is the reason other astronomers are waiting to be convinced. “I agree with the authors that it’s appropriate to consider an interpretation based on rings,” says Eric Ford, an expert on exoplanets at Penn State. The idea that the outer parts would condense into moons relatively quickly, however, means that we’re seeing the rings at their full extent during a very narrow window of existence—the sort of coincidence that scientists don’t love to see. “Whenever your explanation involves catching something during a phase that won’t last very long,” Ford says, “it’s a little concerning.”

MORE Cousins of Earth Found Deep in Space

Much of the doubt could be erased if astronomers could see the rings pass by again on another orbit around the star. Unfortunately, that hasn’t happened: they’ve got only the single passage back in 2007, meaning the exoplanet is on a relatively long orbit. “We think it’s at least ten or 15 years,” says Kenworthy.

They don’t know for sure, though, and since it’s tough to keep big telescopes aimed at this one star hoping for another passage, the astronomers have recruited members of the high-end amateur group, the American Association of Variable Star Observers, to monitor the situation. They’re also going back through digitized versions of old images from observatories around the world, looking for evidence of other stars that faded mysteriously for a while without explanation. “Now that we know what we’re looking for,” Mamajek says, “we might find that there are lots of them out there.”

They might, that is, if they’re really seeing rings. “I keep telling people, ‘if you can think of a better explanation, please let me know,'” Mamajek says, and he means it. So far, he has no takers. “The signal is very strong,” says Harvard’s David Kipping, who is doing his own search for exomoons, “and its difficult to believe the instrument could misbehave on such a huge scale. I think many of us find the signal interesting,” he says. That, by itself, is enough to keep the astronomy community looking.

Read next: SpaceX, Boeing on Track to Get Astronauts into Space by 2017

Listen to the most important stories of the day.

More Must-Reads from TIME

Contact us at letters@time.com