Astronomers confirm most distant object in our solar system, which takes 1,000 years to go round the sun

Rob Waugh
·3-min read

Watch: The furthest object in the solar system has just been confirmed and it’s FarFarOut there

A 250-mile wide object lurking 132 times further from the sun than Earth is the most distant object found so far in our solar system.

The faint object was first spotted in January 2018 by the Subaru Telescope on Maunakea in Hawai'i and nicknamed "Farfarout" – but its orbit was not confirmed.

The International Astronomical Union's (IAU) Minor Planet Center in Massachusetts announced today that it has given Farfarout the provisional designation 2018 AG37.

David Tholen of the University of Hawai‘i said: “Farfarout takes a millennium to go around the Sun once. Because of this, it moves very slowly across the sky, requiring several years of observations to precisely determine its trajectory.”

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The discoverers of Farfarout say more objects are out there to be discovered, and that its distance record might not stand for long.

Scott Sheppard of the Carnegie Institution for Science said: “The discovery of Farfarout shows our increasing ability to map the outer solar system and observe farther and farther towards the fringes of our solar system.

Farfarout is 132 astronomical units from the Sun, which is 132 times farther from the Sun than Earth is (NSF Noirlab)
Farfarout is 132 astronomical units from the Sun, which means it is 132 times farther from the Sun than the Earth is. (NSF Noirlab)

“Only with the advancements in the last few years of large digital cameras on very large telescopes has it been possible to efficiently discover very distant objects like Farfarout.

“Even though some of these distant objects are quite large – the size of dwarf planets – they are very faint because of their extreme distances from the sun. Farfarout is just the tip of the iceberg of objects in the very distant solar system.”

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The team estimates that the very faint object is 250 miles wide, putting it at the low end of possibly being designated a dwarf planet by the IAU.

When it was first spotted, its discoverers could tell it was very far away, but they weren’t sure exactly how far.

Farfarout compared to other objects in the Solar System (NSF Noirlab)
Farfarout compared with other objects in the solar system. (NSF Noirlab)

Sheppard said: “At that time we did not know the object’s orbit as we only had the Subaru discovery observations over 24 hours, but it takes years of observations to get an object's orbit around the sun.”

“All we knew was that the object appeared to be very distant at the time of discovery.”

They have now confirmed that Farfarout currently lies 132 astronomical units (au) from the sun, which is 132 times farther from the sun than Earth is. (For comparison, Pluto is 39 au from the sun, on average.)

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Farfarout is even more remote than the previous solar system distance record-holder, which was discovered by the same team and nicknamed “Farout”.

The orbit of Farfarout is quite elongated, taking it 175 au from the sun at its farthest point and around 27 au at its closest, which is inside the orbit of Neptune.

Because its orbit crosses Neptune’s, Farfarout could provide insights into the history of the outer solar system.

Trujillo said: “Farfarout was likely thrown into the outer Solar System by getting too close to Neptune in the distant past. Farfarout will likely interact with Neptune again in the future since their orbits still intersect.”

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