There’s a new object in the distant reaches of our solar system, and it might just offer clues to a long-standing cosmic mystery. Astronomers have cataloged a frozen minor planet called 2017 OF201, and while it might not be the elusive ninth planet that some have posited exists, its unusual orbit has scientists paying close attention.
2017 OF201 is what’s known as a trans-Neptunian object, or TNO, which means it orbits the Sun beyond Neptune. With a diameter estimated between 290 and 510 miles, it could be one of the largest minor planets discovered in recent years. At its upper size, it even approaches the scale of Ceres, the largest object in the asteroid belt.
What really sets 2017 OF201 apart, though, is its orbit. The minor planet swings as far as 838 astronomical units (AU) from the Sun. For context, Earth sits at 1 AU, and Neptune, the most distant known planet, orbits at 30 AU. That makes 2017 OF201 almost 30 times farther out than Neptune at its most distant point.
This kind of orbit earns the object a spot in the category of extreme trans-Neptunian objects (ETNOs). These bodies have long fueled speculation about hidden influences in the outer solar system, most notably the possibility of a ninth planet now that Pluto isn’t considered one. Some scientists believe the clustering of these far-out orbits points to the gravitational pull of an undiscovered world far beyond Neptune.
Often dubbed “Planet Nine,” the proposed world could be more than six times the mass of Earth and take over 7,000 years to orbit the Sun. Although 2017 OF201 isn’t large enough to fit that description, it could be part of the trail that leads to it. The discovery, like others before it, helps scientists model the forces shaping the solar system’s outer edge.
The solar system remains a dynamic and mysterious place. Every new object like 2017 OF201 adds a piece to the puzzle. Whether or not we ever actually solve the mystery of Planet Nine, though, remains to be seen.
