Just when we thought we knew all the worlds in the Solar System, astronomers have discovered a new object that could rewrite the cosmic map.

This icy world, temporarily named 2017 OF201, could turn out to be a distant cousin of Pluto – and scientists mean “distant” literally. At its furthest point, it is more than 1,600 times farther from Earth than the Sun. At its closest point, it is still 44.5 times farther from Earth.

What makes 2017 OF201 unique is its highly elongated path around the Sun, which takes an incredible 25,000 Earth years to complete. By comparison, Pluto orbits the Sun every 248 Earth years.

How this object ended up at the edge of the Solar System is a mystery.

 Perhaps it was the result of close encounters with giant planets such as Jupiter or Neptune, which threw it into a wide orbit. Or perhaps, when it was first ejected, it entered the so-called Oort Cloud before returning. The Oort Cloud is believed to be a sphere of ancient icy objects surrounding the Solar System. The Oort Cloud is believed to be a sphere of ancient icy objects surrounding the Solar System. NASA says the cloud remains a theory because the comets in it have been too faint and distant to be observed directly.

The Minor Planet Center of the International Astronomical Union, which catalogs new moons and other small bodies in the Solar System, announced the discovery on May 21. With a width of about 700 kilometers, 2017 OF201 can be classified as a dwarf planet. Pluto is also classified as a dwarf planet since its demotion from ninth planet in 2006.

“Although advances in telescopes have allowed us to explore distant parts of the universe, there is still much to discover about our own solar system,” said Sihao Cheng, a researcher at the Institute for Advanced Study who led the discovery.

Cheng, along with Princeton University graduates, discovered the possible dwarf planet while searching for a potential “Planet 9” — a hypothetical hidden world whose gravitational influence could be causing the strange clustering of distant objects beyond Neptune.

The team used computer programs to review years of space images taken by the Victor M. Blanco telescope in Chile and the Canadian-French telescope in Hawaii. By connecting bright spots that move slowly across the sky, they were able to identify it.

But 2017 OF201 is a strange outlier because it does not follow the grouping pattern of other trans-Neptunian objects.

“The existence of 2017 OF201 may suggest that Planet 9 or Planet X does not exist,” one of the collaborators, Jiaxuan Li, wrote on his personal website.

The discovery also calls into question many scientists' understanding of the outer Solar System. The area beyond the Kuiper Belt, where the object is located, was previously thought to be fairly empty. NASA's New Horizons probe, which photographed Pluto and its moons in 2015, has since increased that distance more than twofold, although surprisingly it has not yet reached the end of the belt.

This could mean that the spacecraft will travel billions more kilometers before reaching interstellar space — a region no longer influenced by solar radiation and particles. In 2019, New Horizons photographed an icy red dumbbell-shaped object called Arokot, the most distant object the spacecraft has ever encountered.

If 2017 OF201 spent just 1% of its orbit close enough for humans to detect it, this could mean that what lies beyond the Kuiper Belt is not so empty after all.

“The existence of this single object suggests that there may be about a hundred other objects with similar orbits and sizes. They are just too far away to be detected now,” Cheng explained. | BGNES