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Science and Innovations

Newly Discovered Solar System Objects Point to ‘Planet Nine’


An astronomer at Northern Arizona University announced the discovery of three new objects at the far edge of the solar system. They help narrow down the search for the hypothetical Planet Nine.

The objects were found by NAU astronomer Chad Trujillo and his colleagues. They run the world’s largest survey for so-called “extreme objects” that orbit the sun beyond the Kuiper Belt.

Trujillo says, “We’ve been looking for all kinds of things on the outer edge but it’s only been in the last year or two where we’ve really started to notice that some of these extreme objects seem to be pointing to the possibility of something big out there.”

Planet Nine is thought to be a massive ice giant lurking beyond Neptune. Trujillo and his colleague Scott Sheppard proposed its existence in 2014. Earlier this year two Caltech astronomers strengthened the case for Planet Nine based on the strange orbits of a cluster of space rocks.

Two of the new objects also have odd orbital alignments. That implies they’re influenced by the undiscovered planet. Trujillo says finding more objects like these will speed up the search.

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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