Astronomers Discover New Dwarf Planet in the Distant Reaches of Our Solar System

Astronomers have recently identified a new dwarf planet, named 2017 OF201. This celestial body appears to measure approximately 700 kilometers in diameter, qualifying it as a dwarf planet. What makes it even more intriguing is its orbit, which reduces the likelihood of the existence of the elusive Ninth Planet.

«The aphelion of this object — the farthest point in its orbit from the Sun — is over 1,600 times the radius of Earth’s orbit,» states astrophysicist Sihao Cheng from the Institute for Advanced Study in Princeton, New Jersey. «Meanwhile, its perihelion — the closest point to the Sun — is 44.5 times greater than Earth’s orbital radius, analogous to Pluto’s orbit.»

Cheng and his colleagues are engaged in a campaign to search for and study trans-Neptunian objects (TNOs), which are chunks of rock and ice orbiting the Sun beyond Neptune at a distance of about 30 astronomical units (a.u.). Locating these objects is challenging since they are tiny, cold, and reflect very little light.

In recent years, more powerful instruments have emerged that can penetrate the Kuiper Belt and beyond, allowing for the detection of individual objects. The furthest object identified to date is FarFarOut, a rock approximately 400 kilometers wide, located at a distance of 132 a.u.

Cheng and his team discovered 2017 OF201 in archival data collected by the Dark Energy Camera Legacy Survey (DECaLS) and the Canada-France-Hawaii Telescope (CFHT). Between 2011 and 2018, DECaLS and CFHT observed 2017 OF201 a total of 19 times, enabling the team to characterize the object and its orbit with a high level of confidence.

Initially observed at a distance of 90.5 a.u., 2017 OF201 is more than twice as far from the Sun as Pluto, which orbits at around 40 a.u. Its orbit is an elongated ellipse, bringing it as close as 44 a.u. and pushing it out to 1,600 a.u. — into the inner Oort Cloud, a region of rocks and ice that surrounds the solar system’s outer limits.

This provides one of the strongest arguments against the existence of a Ninth Planet. It also suggests that there are likely many more such objects in the Kuiper Belt and beyond that have yet to be discovered.

«2017 OF201 spends only one percent of its orbital time close enough for us to detect it. The presence of this single object indicates that there may be a hundred or so others with similar orbits and sizes; they are simply too distant for us to find,» adds Cheng.