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Science and Innovations

NASA Invites the Public to Search for ‘Planet Nine’


The public can now join the hunt for the elusive Planet Nine, a massive planet astronomers believe might be hidden beyond Neptune.

NASA scientists put a hundred thousand “flipbooks” online—little movies that show the same patch of the night sky over time. It’s an enormous amount of data, which is why they asked the public to help search for moving objects in the images.

Astrophysicist Marc Kuchner of NASA Goddard Space Flight Center launched the project. “We are simultaneously searching this data using computers,” he says. “However, the computers get stuck in crowded star fields. You end up having to look at the images by eye anyway. So we figured we should just ask for some help.”

Planet Nine has not yet been observed, but scientists think they see its gravitational effects on objects in the Kuiper Belt. Chad Trujillo of Northern Arizona University is one of the astronomers who proposed its existence. He says it’s a good idea to enlist the public.       

“That would be a great thing to happen; you know, if an interested citizen found the ninth planet, they would be helping to discover one of the greatest science stories of our time,” he says. 

Example of a flipbook with a brown dwarf moving across it.

Trujillo cautions it may turn out Planet Nine doesn’t exist. But the project will likely turn up other interesting objects, such as “rogue worlds” that drift in the spaces between stars.

More than 22,000 people have already signed up for the project, called “Backyard Worlds.” So far they’ve marked about 200 objects for further study.

The idea of “blinking” images back and forth to find moving objects isn’t new. Almost 90 years ago, a scientist at Lowell Observatory in Flagstaff used this method to find Pluto, the original planet nine.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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