"This is quite a watershed moment in the field of planetary science," researcher Alan Stern told Newsweek.
The rocky world is located around 4 billion miles from Earth.
Ultima Thule is located around 4 billion miles away from the Sun.
The distant object, about 4 billion miles from the sun, lies in the Kuiper Belt.
"The instinctive, the passionate, the almost unconscious side [of my brain] takes over. As soon as I heard the words…I could hear the melody in my head. It just somehow took shape."
"This is the most distant exploration of any world in history," Alan Stern said. "We are the Lewis and Clark of our era."
"We're seeing the threshold between being in the solar neighborhood and being in the galaxy."
The spacecraft's target is more than four billion miles away from Earth.
It also means "beyond the limits of the known world."
Strange signals suggest MU96 has a "moonlet."
2014 MU69 lacks the sort of pizzazz NASA looks for in a destination's name.
Don't cry too much about Cassini. Upcoming missions are going to Mars, Mercury, the Sun, Europa and several asteroids.
Located beyond Pluto, 2014 MU69 will be the farthest object ever encountered by any spacecraft.
Just three months after the historic flyby, the New Horizons team has a paper coming out in the journal "Science."
Program scientist Curt Niebur explains new data from NASA's New Horizons mission.
NASA has released an image taken by the New Horizons spacecraft just 15 minutes after its Pluto flyby.
Continuing a long tradition of space program conspiracy theories, 'Pluto Truthers' claim NASA is faking it.
One day after the flyby, the New Horizons team makes an important discovery about geology based on a detailed surface image.
The spacecraft's team waited anxiously for it to "let us know it's OK."
Videos, tweets and a Google doodle honor the historic moment in space exploration.
NASA published its most detailed image yet, taken one day before the flyby. Even better images are still to come.
NASA is set to make history shortly after 7:30 a.m. on Tuesday when the New Horizons spacecraft zooms past Pluto.