NASA is getting closer and closer to a billion-mile world of Puto

It's getting bigger.

Last week, NASA released photos of the New Horizons spacecraft approaching an ancient and little-known object in the deep space called Ultima Thule.

Ultima revolves around the sun a billion miles after Pluto, and NASA plans to move closer to the distant object shortly after midnight on January 1, 2019.

It will be the most distant encounter of humanity with another world.

"What Ultima will reveal – no one knows," NASA's global scientist Alan Stern wrote last week.

NASA thinks that Ultima is a type of ice mass formed 4.5 billion years ago, when creating our solar system.

But since then, hovering in the confines of the deeply cold solar system, Ultima is presumed to have been largely preserved in its primitive virgin state, allowing scientists to see the distant past.

"In reality, Ultima should be a useful window on the early stages of planet formation and on the state of the solar system more than 4.5 billion years ago," Stern said.

Ultima is officially classified as an "object of the Kuiper Belt", which is a ring of icy worlds that surrounds the solar system beyond the last great planet, Neptune. This is a "remnant region of the first history of the solar system," says NASA.

Ultima is already revealed a little mysterious.

From previous images, scientists learned that Ultima probably had a strange, non-spherical shape. But as New Horizons approaches, the structure of light reflected by Ultima, or its curve of light, is incoherent. With most other objects, these patterns of light are repeated as objects rotate.

"It's really a puzzle," Stern said in a statement.

Other New Horizons scientists said to themselves that a cloud of dust or moons "falling" around Ultima could produce the strange curve of light.

But, there is one thing that is almost certain.

On December 15, the Stern team concluded that there was no obstruction between New Horizons – a triangular spacecraft 7 feet long and 9 feet high – and Ultima Thule.

Stern told NASA that the deep space probe is now "Go" to approach Ultima closely.

In the summer of 2015, New Horizons piloted by Pluto. He captured unprecedented details of the dwarf planet, its mountains, its cliffs and its icy plains. The exploration craft flew 7,000 miles from the surface of Pluto.

But he will be much closer to Ultima Thule, crossing 2,200 miles above this little-known object.

The first images are expected back early on New Year's Day, about 30 minutes after the balloon drops at Times Square.

"The overflight of Ultima Thule will be fast, challenging and will generate new knowledge," Stern said.

"Being the most distant exploration of all that exists in history, it will also be historic."

We are going to watch.

To watch the images arrive when approaching Ultima, tune a livestream from NASA TV starting around 12:15, January 1, 2019.