'Meet Ultima Thule,' the most distant object visited by a spacecraft

Just over a day after NASA’s New Horizons spacecraft zipped by Ultima Thule, scientists revealed their preliminary findings of the distant object.

Object in outer solar system looks like a red snowman, preliminary findings suggest

The first colour image of Ultima Thule, taken at a distance of 137,000 kilometers at 4:08 Universal Time on Jan. 1, highlights its reddish surface. At left is an enhanced colour image taken by the Multispectral Visible Imaging Camera, produced by combining the near infrared, red and blue channels. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Just over a day after NASA's New Horizons spacecraft zipped by Ultima Thule, scientists have revealed their preliminary findings of the distant object.

Ultima Thule, or more formally 2014 MU69, is a member of the Kuiper Belt, a ring-shaped region of icy objects orbiting the sun. The area begins just beyond the orbit of Neptune, more than 4.4 billion kilometres from the sun, and is believed to extend to about eight billion kilometres from the  sun.

At a press conference at the Johns Hopkins Applied Physics Laboratory in Laurel, Md., on Wednesday, New Horizons principal investigator Alan Stern of the Southwest Research Institute​ called up a slide of the last image of Ultima Thule shown to the public.

"That image is so 2018," said Stern. He then pulled up the most recent image taken by New Horizons on Jan.1. "Meet Ultima Thule." 

So far, scientists have learned that Ultima is red, with a rotational period of roughly 15 hours. It is also a bilobate or contact binary object, meaning that it is composed of two separate objects that are now joined. Initial images suggested it resembled a bowling pin.

"Let me say, that bowling pin is gone. It's a snowman if it's anything at all," Stern said amid laughter from the gathered media.

Since there are two separate lobes to the object, the team felt they needed to come up with a name for each. They named the larger region Ultima and the smaller one Thule. The entire object is 32 kilometres long and 16 kilometres wide.

Scientists are keen to study Ultima Thule as it lives in a region that has been relatively untouched since the formation of the solar system, which in turn helps them better understand planetary formation.

A formal name will be given by the International Astronomical Union's Minor Planet Center.

Data from the New Horizons flyby of Ultima Thule will be coming in for about two years.

"This mission has always been about delayed gratification," Stern said on Tuesday. "It took us 12 years to sell it. It took us five years to build it. It took us nine years just to get to the first target."

Next week, the spacecraft will be unable to transmit any data due to radio interference from the sun. Stern said the spacecraft will resume transmitting in mid-January.

The main priorities for the research is mapping Ultima Thule's surface, as well as looking for any potential moons and rings.

New Horizons was launched in 2006 on a mission to fly by Pluto. In 2015, the spacecraft passed Pluto, providing the first images of a world once considered our ninth planet.


Nicole Mortillaro

Senior reporter, science

Based in Toronto, Nicole covers all things science for CBC News. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books. In 2021, she won the Kavli Science Journalism Award from the American Association for the Advancement of Science for a Quirks and Quarks audio special on the history and future of Black people in science. You can send her story ideas at