Snowman-shaped object on edge of solar system may explain how planets formed, finds Hopkins' New Horizons mission

This image made available by NASA on Wednesday, Jan. 2, 2019 shows images with detail and color information showing Ultima Thule, about 1 billion miles beyond Pluto. The New Horizons spacecraft encountered it on Tuesday, Jan. 1, 2019.

The scientists running NASA’s New Horizons mission showed off the first detailed images Wednesday of an object 4 billion miles away in space. It looked like a blurry, reddish snowman.

Despite that primitive appearance — if not because of it — they said the object nicknamed Ultima Thule could offer profound new insight into how the planets formed more than 4½ billion years ago.


“We should think of New Horizons as a time machine,” said Jeff Moore, the mission’s lead geology and geophysics scientist. The spacecraft “has brought us back to the very beginning of solar system history.”

New Horizons, designed by and managed from the Johns Hopkins Applied Physics Laboratory in Laurel, has been speeding toward the edge of the solar system for 13 years. It zoomed past Pluto — collecting numerous photos and reams of information about the now dwarf planet — in July 2015, and reached Ultima Thule early on New Year’s Day.


It was the first exploration of such a primitive — and distant — planetary object in human history.

It will take nearly two years to beam all of the images and data the piano-sized spacecraft collected back to Earth. The first batch that scientists revealed Wednesday was only a taste, but it was a tantalizing one, they said.

New Horizons project scientist Hal Weaver of Johns Hopkins University Applied Physics Laboratory at a press conference after the team received confirmation from the New Horizons spacecraft that it had completed a flyby of Ultima Thule at Johns Hopkins APL in Laurel.

It showed Ultima Thule, formally known as 2014 MU69, is actually a pair of reddish spheres that have been fused together by gravity, they said. That supports the idea that billions of years ago, amid the swirling chaos of the early solar system, matter collected in larger and larger clumps until their gravity was strong enough to develop into planets and moons.

Ultima Thule is one of few building blocks left from that process that humans have explored — and the only pristine example from that time.

“What this spacecraft and this team accomplished is unprecedented,” said Alan Stern, the mission’s principal investigator, before unveiling the first images.

But even as the researchers celebrated their triumph of celestial navigation, the mission drew unwanted attention for the name Ultima Thule.

Mission organizers have been criticized for calling the object by a name that Nazis used for the mythical birthplace of the Aryan race. But Stern said that the phrase Ultima Thule is hundreds, if not a thousand, years old, and is apropos because it means "beyond the known universe" in Latin.

"Just because some bad guys once liked that term,” he said, “we’re not going to let them hijack it.”


Instead, they focused on what the new images told them about planetary science.

Scientists already expected that the 19-mile-long Ultima Thule had two lobes to it, and even wondered if it was a pair of objects orbiting each other. Data that New Horizons collected as it approached its target suggested that Ultima Thule was bowling-pin-shaped and spinning like a propellor.

Instead, the first images beamed down from the spacecraft show it resembles a snowman — or even the BB-8 droid robot from the “Star Wars” film series. The larger of the pair, which scientists named Ultima, is three times bigger than the smaller one, dubbed Thule. Ultima Thule rotates about once every 15 hours, the scientists determined.

Moore said it appears the two spheres came together gently, at speeds of perhaps 1 or 2 mph — not in some violent collision in space.

“If you have a collision with another car at those speeds, you may not bother to fill out the insurance forms,” he joked.

And the objects adjoin at a narrow neck, but evidence suggests they are held together by gravity and not some other force, Stern said.


“You can see they’re clearly two separate objects that have come together,” said Cathy Olkin, the mission’s deputy project scientist. “This is exactly what we need to move the modeling work on planetary formation forward.”

There are no obvious signs Ultima Thule has been significantly disturbed since it came together as the solar system formed, the researchers said. They could not see any large craters on its surface, though they said some could be revealed in images taken from different angles. The pictures released Wednesday were taken about an hour before New Horizons made its closest approach to Ultima Thule, when the spacecraft had the sun behind it and its target in front.

And the images confirmed what observations using the Hubble Space Telescope had suggested as New Horizons scientists scouted Ultima Thule — that, like parts of Pluto and its moon Charon, it has a rusty hue.

Scientists won’t know what substances cover its surface until they process more data that was expected to arrive on Earth on Wednesday, but they speculated it could be methane, nitrogen or other organic material.

Ultima Thule is likely similar to some comets and asteroids that scientists have studied as they pass through the inner solar system. But unlike those objects, which have encountered more space debris and endured the sun’s heat, Ultima Thule is thought to be mostly unchanged since it formed. That’s why it already holds such lessons about the formation of the planets.

“This is the first object we can clearly tell was born this way, and didn’t evolve to look this way,” Stern said. “This really puts the nail in the coffin — now we know this is how these kinds of objects in many cases form.”


He added that if there was any shock from the Ultima Thule fly-by, it was how fortunate the scientists were for finding it in the Kuiper Belt. The massive area of swirling objects at the edge of the solar system also contains Pluto.

“I’m surprised that, more or less picking one Kuiper Belt object out of the hat, that we were able to get such a winner as this,” he said. “It’s going to revolutionize our knowledge of planetary science.”