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New Horizons returns sharp images of Ultima Thule © NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Arrokoth: Minor planet known as Ultima Thule given official name

Published: 13th November, 2019 at 10:04
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Arrokoth means ‘sky’ in the language of the Native American Powhatan people, NASA said.

The most distant world ever explored – 4 billion miles away – finally has an official name, Arrokoth, replacing its nickname 'Ultima Thule'. That means “sky” in the language of the Native American Powhatan people, NASA said.


NASA’s New Horizons spacecraft flew past the snowman-shaped body on New Year’s Day, three and a half years after exploring Pluto. This small icy world lies a billion miles beyond Pluto.

“The name Arrokoth reflects the inspiration of looking to the skies,” lead scientist Alan Stern of Southwest Research Institute said in a statement, “and wondering about the stars and worlds beyond our own.”

New Horizons is operated from Johns Hopkins University’s Applied Physics Lab in Laurel, Maryland. The Hubble Space Telescope — which discovered Arrokoth in 2014 — has its science operations in Baltimore.

Read more about New Horizons:

The New Horizons team got consent for the name from Powhatan tribal elders and representatives, according to NASA. The International Astronomical Union and its Minor Planet Centre approved the choice.


Arrokoth is among countless objects in the Kuiper Belt, beyond the orbit of Neptune. New Horizons will observe some of these objects from afar as it makes its way deeper into space.

New Horizons' first sharp image of Arrokoth

In January, the New Horizons spacecraft returned a sharp image of Arrokoth, then known as Ultima Thule, revealing details of its snowman-like shape and its colour.

“The two lobes are perfectly separated, which implies that they must have merged extremely gently. Otherwise, they would have shattered,” said Dr Olivier Hainaut, astronomer at the European Southern Observatory.

“This is not typical for other parts of the Solar System — look at the craters on the Moon for examples of what usually happens!”

Arrokoth’s colour, as well as its shape, holds clues to its nature. “The two lobes seem to be of the same colour, and the surfaces seem very uniform,” observes Dr Hainaut.

“This is also extremely interesting: this suggests the two lobes are constituted of the same material, and that it is rather homogeneous.”

Read more about Arrokoth


Sara RigbyOnline staff writer, BBC Science Focus

Sara is the online staff writer at BBC Science Focus. She has an MPhys in mathematical physics and loves all things space, dinosaurs and dogs.


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