"We think what we're looking at is perhaps the most primitive object that has yet been seen by any spacecraft, and may represent a class of objects which are the oldest and most primitive objects that can be seen anywhere in the present solar system", Mr Moore said.
Carly Howett, New Horizons co-investigator, said: "We can definitively say that Ultima Thule is red".
"What this spacecraft and this team accomplished is unprecedented", said Alan Stern, the mission's principal investigator, before unveiling the first images.
Jeff Moore, New Horizons Geology and Geophysics team lead, said the appearance of Ultima Thule is remarkable. Data that New Horizons collected as it approached its target suggested that Ultima Thule was bowling-pin-shaped and spinning like a propellor. "New Horizons has set a new bar for state-of-the-art spacecraft navigation".
New Horizons passed within 2,200 miles (3,500 kilometers) of Ultima Thule, which lies in the Kuiper Belt some four billion miles from Earth.
In a press conference this afternoon, they've released their latest batch of results.
These two rocks were then pulled together by the extremely weak gravitational forces of each other, nudging together at such slow speeds that initial observations from New Horizons do not reveal any stress fractures or damage from the "collision".
When New Horizons left Earth in 2006, scientists did not even know about Ultima Thule's existence.
Scientists weren't able to confirm the flyby until several hours later. The center image is the high-resolution picture snapped by LORRI at the same time.
The new images show Ultima to be a contact binary, consisting of two separate masses that became stuck together.
It also looks pristine, nearly unchanged since it formed out of a disk of dust and gas that orbited the sun more than 4.5 billion years ago.
When asked about the Nazis' use of the term, Showalter confirmed that he was aware of the usage and said that the New Horizons team and NASA, including its legal department, decided that the original meaning was more prominent and outweighed the less savory connotations. Tholins are also behind the reddish color in a crater on the surface of Pluto's biggest moon, Charon, but scientists say the process behind its deposition on Ultima is likely to be different.
"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 bowling pin image is "so 2018", joked Stern, who is with the Southwest Research Institute.
It will take as long as 20 months for scientists to download and process all the data collected during their brief encounter with Ultima Thule, scientists said.