First Decent Ultima Thule Image Reveals Textbook Contact Binary

Ultima Thule contact binary

Our first look at Ultima Thule was little more than a smudge. Today, that smudge begins to clear. Have a look at the first decent image of Ultima Thule as New Horizons was still 18,000 miles away.

New Horizons Principal Investigator Alan Stern was proud of what the men and women behind the scenes accomplished. “This flyby is a historic achievement. Never before has any spacecraft team tracked down such a small body at such high speed so far away in the abyss of space. New Horizons has set a new bar for state-of-the-art spacecraft navigation.”

In the coming days and weeks, we’ll see much closer views of Ultima Thule.

But today’s look shows us what lurks in the Kuiper Belt. Ultima Thule measures 19 miles 21 miles (UPDATE: It should be 21 miles in length. The official New Horizons blog post states 19 miles, but the slide from today’s news conference says 21) in length and is made up of two round-ish blocks of rock and ice. The bigger sphere is nicknamed Ultima and measures 12 miles across. The smaller is Thule at 9 miles across.

The New Horizons team believe Ultima and Thule slowly collided soon after the solar system was taking shape. They liken it to two cars getting into a fender bender. If the two pieces were moving fast when they collided, they would have bounced off each other.

We also now know that Ultima Thule has a reddish/brown tint to its surface.

We saw similar colors when New Horizons gave us stunning up-close views of Pluto. As more data comes in, scientists will have a better handle on what’s causing it. On Pluto, the culprit was tholins – hydrocarbon molecules formed from the interaction between sunlight and methane. A similar process is likely happening on Ultima Thule.

Jeff Moore, the team lead for the Geology and Geophysics portion of the New Horizons mission, explains why visiting Ultima Thule is so special. “New Horizons is like a time machine, taking us back to the birth of the solar system. We are seeing a physical representation of the beginning of planetary formation, frozen in time,” says Moore. “Studying Ultima Thule is helping us understand how planets form — both those in our own solar system and those orbiting other stars in our galaxy.”

The crazy thing is, Ultima Thule might not be all that special in the grand scheme of things. It was picked because it was bright enough to be discovered and it just happened to be along New Horizons’ path. Other objects in the Kuiper Belt likely look similar.

The good news is New Horizons is healthy enough and has enough juice to visit another one. Stern said during today’s press conference that all systems are still green, and there’s enough power to travel many more millions of miles. As the initial excitement for this flyby dies down, the folks at New Horizons will start putting together a plan to present to NASA for exploring another world.

In the meantime, get ready for even better images and science tomorrow and in the weeks and months ahead.

The Gist
An email newsletter that gets to the point. Crazy idea, right? Sign up today.
The Gist is a few days a week newsletter. No incessant emails. We hate them and that's way too much work.