The legendary New Horizons spacecraft has sent back the most detailed image yet of MU69 — the most distant object a human spacecraft has ever explored.

At some four billion miles from Earth, and one billion miles past Pluto, MU69 (which also goes by "Ultima Thule") has been an object of mystery since its discovery in 2014. But New Horizons finally swooped by the distant object just after the 2019 New Year, uncovering a frozen, snowman-shaped world, composed of two roundish "lobes" that have been stuck together.

"This new image is starting to reveal differences in the geologic character of the two lobes of Ultima Thule, and is presenting us with new mysteries as well," said Alan Stern, principal investigator of the New Horizons mission, in a statement. The mission is is jointly managed by NASA, the Southwest Research Institute, and the Johns Hopkins Applied Physics Laboratory.

"Over the next month there will be better color and better resolution images that we hope will help unravel the many mysteries of Ultima Thule," Stern added in his statement.

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Unlike previous images of MU69, this one clearly shows a deep, 4-mile wide depression on the smaller lobe, as well as a number of craters dotting the surface.

MU69 is a place of true scientific intrigue. It lies in a far-off group of objects, called the Kuiper Belt, that ring the solar system. Temperatures here approach absolute zero (minus 460 degrees Fahrenheit), which is as cold as it gets. Scientists suspect that these ancient objects have been preserved in relatively pristine condition since the beginnings of the still-forming solar system, some 4 billion years ago. 

Observing MU69, then, is like witnessing our solar system origins, long before Earth became a habitable place. 

"The Kuiper Belt is just a scientific wonderland," Stern said just days before New Horizons sent back its first images.

“We've never, in the history of spaceflight, gone to a target that we know less about," Stern added.

New Horizons beamed back these images on January 18 and 19. At billions of miles away, it takes around 6 hours for the data to arrive back on Earth.

Meanwhile, the New Horizons spacecraft continues to hurtle deep into the outer realms of the solar system, at 31,500 mph.