'Snowman' shape of distant Ultima Thule revealed

Oscar Cross
January 3, 2019

Since New Horizons sent its first post-flyby message, the mission team slowly but surely has been receiving a trickle of data on Ultima Thule (pronounced TOOL-ee, a Latin phrase meaning "a place beyond the known world"), which is located a staggering 4.1 billion miles (6.6 billion km) from Earth.

May wrote an anthem for New Horizon's flyby of Ultima Thule as a tribute to a glimpse beyond our solar system.

"I had never heard the term Ultima Thule before we had our naming campaign", Mark Showalter, a planetary astronomer at the SETI Institute and investigator on the New Horizons mission who led the naming process, told me at Newsweek in March.

New Horizons rocketed from Cape Canaveral, Florida, in 2006.

The new colour image also revealed it to be definitively red, like the top of Pluto's moon Charon. "It will be by far the most distant object we have ever seen at close quarters, through the images which the space craft will beam back to Earth".

And while the first images may still be a bit disappointing, the best pictures will be arriving in the days and weeks ahead. They named the larger region Ultima and the smaller one Thule.

Included in this will be a series of much higher-resolution images that will provide an even greater look at Ultima Thule, now the farthest object from Earth to ever be photographed by a spacecraft.

Mutual gravitational attraction keeps them married despite their gentle, 15-hour rotation.


The Long-Range Reconnaissance Imager, or LORRI, had "28,000 pixels on the target ... which way beats six pixels", Stern joked referring to the fuzzy, bowling-pin picture that was released the day before. The improved resolution also draws attention to the object's "neck", where the two lobes are connected.

"It's a snowman", mission principal investigator Alan Stern, a planetary scientist from the Southwest Research Institute, said during a news briefing here at Johns Hopkins University's Applied Physics Laboratory.

Ultima Thule was once two separate space rocks that joined together, known as a contact binary.

He added: "These are the only remaining basic building blocks in the back yard of the solar system that we can see that everything else that we live on, or receive through our telescopes, or visit with our spacecraft, were formed from".

Scientists said there were no obvious impact craters in the latest photos but a few apparent "divots" and suggestions of hills and ridges.

Ultima Thule has a mottled appearance the colour of light brick. In 2015, the spacecraft passed Pluto, providing the first images of a world once considered our ninth planet. It's not fish or fowl.

"Everything that we're going to tell you [today] is just the tip of the iceberg", Dr Stern said.

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