Possible dwarf planet found at edge of solar system

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory about the possibility of a giant ninth planet. The dwarf planet's existence also opens the likelihood of many more like it in our solar system waiting to be found.

A planet far, far away

A possible dwarf planet, like Pluto, has been observed in our solar system, according to a preprint published in arXiv. The area of space where this planet was found was previously thought empty. The potential planet, which has been temporarily called 2017 OF201, takes "more than 24,000 years to travel around the sun just once along a highly elliptical orbit, coming as close as 4.2 billion miles and moving as far out as 151 billion miles," said The New York Times. It is also about only 430 miles wide.

A dwarf planet is "classified as a celestial body that orbits the sun that has enough mass and gravity to be mostly round, but unlike other planets, has not cleared its orbital path of asteroids and other objects," said NBC News. Its discovery was "not very different from how Pluto was discovered," said Sihao Cheng, a member at the Institute for Advanced Study who led the research team for the study, to NBC News. "This project was really an adventure." Scientists studied archival data from the Blanco telescope in Chile and the Canada-France-Hawaii telescope in Hawaii and tracked 2017 OFF201's motion for seven years.

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The potential dwarf planet may not be the only one. "The discovery of 2017 OF201 suggests a population behind it with hundreds of objects possessing similar properties because the probability for 2017 OF201 to be close enough and detectable is only 0.5% given its wide and eccentric orbit," said the preprint.

A world unknown

There has been a theory among scientists that there is a "huge and mysterious planet lurking in the darkness at the edge of our solar system, evading all our efforts to spot it," said CBS News. This potential planet has been called Planet Nine or Planet X. A potential ninth planet could "explain an unusual clustering of objects and other anomalies observed in the outer solar system." Celestial objects previously found beyond Neptune had unusual orbits, which "hinted that another large mass in the outer solar system was gravitationally pulling on the miniworld[s]," said Live Science.

However, rather than finding Planet Nine, researchers found 2017 OF201, which may disprove the Planet Nine theory. The researchers found that the dwarf planet's "orbit would remain stable for the next billion years or so — if there were no Planet Nine," said the Times. If there were one, that Planet Nine would "nudge the closest part of 2017 OF201's trajectory inward until Neptune flung it out of the solar system." Because 2017 OF201 is there, that could be an "argument that Planet Nine is not." Despite this, "people have considered a whole host of different orbits for these hypothetical planets," Chad Trujillo, an astronomer at Northern Arizona University, said to Science News. "This object being incompatible with one is not [detrimental] to Planet X."