When the two will meet, on January 1, the small ball, affectionately known as Ultima Thule, will become the farthest celestial object ever explored by humanity.
New Horizons will make its closest approach in the wee hours of January 1 - 12:33 a.m. EST.
FILE - This composite image made available by NASA shows the Kuiper Belt object nicknamed "Ultima Thule", indicated by the crosshairs at center, with stars surrounding it on August 16, 2018, made by the New Horizons spacecraft.
As mentioned, the 6.5 billion mile distance means that signals from New Horizons take about six hours to reach Earth.
New Horizons, which launched in 2006, previously captured stunning images of Pluto when it flew by the dwarf planet in 2015. At the very least, the nuclear-powered New Horizons will continue to observe objects from afar, as it pushes deeper into the Kuiper Belt. In temperatures that cold, the rocks have essentially been frozen in time for billions of years. Its official designation is 2014 MU69.
A camera on board the New Horizons spacecraft is now zooming in on Ultima Thule, so scientists can get a better sense of its shape and configuration - whether it is one object or several. In classic and medieval literature, Thule was the most distant, northernmost place beyond the known world.
More information will be available from New Horizons as early as the end of the week, but according to mission leaders, it will be more than a year and a half before all the data downloads.
Dr Alan Stern, the NASA New Horizons mission's head, said: "What will Ultima reveal?" Ultima Thule might help scientists to study the formation history of our solar system.
Call it the little spacecraft that could. change what we know about our galaxy. "New Horizons is on the hunt to understand these objects, and we invite everyone to ring in the next year with the excitement of exploring the unknown". In 2017, scientists determined that it isn't spherical, but more elongated. The best pictures won't be possible until New Horizons is more or less on top of the object, filming it with its onboard cameras. It is much smaller than Pluto, but its exact size and shape are unknown. Planetary bodies in the Kuiper Belt are thought to be unchanged from when the solar system was formed 4.5 billion years ago.
Visitors will be able to catch the reactions and live simulations of the flyby on the New Horizons mission website. As distant as it is, Pluto is barely in the Kuiper Belt, the so-called Twilight Zone stretching beyond Neptune.
So what can we expect?
Just after midnight on January 1st will be the first time an object like this has been seen at the edge of the Solar System.
The spacecraft has already started taking photos of its mark. "That's one of the things we're really excited to learn". Stern said that scientists will know the answer to these questions in just a few days' time. "Being the most distant exploration of anything in history, it's also going to be historic".