New Issue: Orbital Catastrophe Ahead? Read Now

In the Hunt for Planet Nine, Astronomers Eye a New Search Technique

“Shifting and stacking” method could unveil the elusive world and other objects in the outer solar system

Artist’s impression of an as-yet-undiscovered ninth planet in the outer solar system.

Join Our Community of Science Lovers!

Finding Planet Nine may require looking at telescope images in a different light.

Astronomers are vetting a “shifting and stacking” technique that could aid the hunt for the putative world, which some researchers think lurks undiscovered in the far outer system, way beyond Pluto’s orbit. 

The strategy involves shifting space-telescope images along sets of possible orbital paths, then stacking the photos together to combine their light. The technique has already been used to discover some moons in our solar system, and it could potentially spot Planet Nine—also known as Planet X, Giant Planet Five or Planet Next—and other extremely farflung objects, researchers said.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


“You really can’t see them without using this kind of method,” Malena Rice, an astronomy Ph.D. student at Yale University in Connecticut, said in a statement. “If Planet Nine is out there, it’s going to be incredibly dim.”

Rice is lead author of a new study that put the method into action. She and co-author Greg Laughlin, an astronomy professor at Yale, shifted and stacked images captured by NASA’s Transiting Exoplanet Survey Satellite (TESS), which hunts for alien worlds from Earth orbit. 

In a test, the researchers found the faint signals of three known trans-Neptunian objects (TNOs)—small bodies that circle the sun beyond Neptune’s orbit—in shifted and stacked TESS images. The scientists then conducted a blind search of two distant patches of sky, turning up 17 new TNO candidates.

“If even one of these candidate objects is real, it would help us to understand the dynamics of the outer solar system and the likely properties of Planet Nine,” Rice said. “It’s compelling new information.”

The researchers are currently working to confirm the 17 candidate TNOs, using imagery captured by ground-based telescopes. 

TNOs are bread crumbs that could lead to the way to Planet Nine. Researchers have inferred the hypothetical world’s existence from the odd orbits of some TNOs, which they say are clustered in a way that strongly suggests sculpting by a big, farflung “perturber.” The data indicate a planet five to 10 times more massive than Earth, orbiting the sun hundreds of times farther away than our world does.

Not everyone is on board with this interpretation, however. Some scientists think the TNOs’ odd clustering arises from the combined gravitational influence of their many minuscule neighbors, not a single big object. 

The new study has been accepted by The Planetary Science Journal. Rice presented the results today (Oct. 27) at the annual meeting of the American Astronomical Society’s Division for Planetary Sciences, which is being held virtually this year.

Copyright 2020 Space.com, a Future company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Mike Wall has been writing for Space.com since 2010. His book about the search for alien life, “Out There,” was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor’s degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz.

More by Mike Wall

SPACE.com is the premier source of space exploration, innovation and astronomy news, chronicling (and celebrating) humanity's ongoing expansion across the final frontier.

More by SPACE.com

Subscribe to Support Independent Journalism

Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.

When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.

Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber

Thank you,

Jeanna Bryner, Editor in Chief, Scientific American

Subscribe