LAUREL, Md. – A NASA spacecraft 4 billion miles from Earth yielded its first close-up pictures Wednesday of the most distant celestial object ever explored, depicting what looks like a reddish snowman.
Ultima Thule, as the small, icy object has been dubbed, was discovered to consist of two fused-together spheres, one of them three times bigger than the other, extending about 21 miles in length.
NASA's New Horizons, the spacecraft that sent back pictures of Pluto 31/2 years ago, swept past the ancient, mysterious object early New Year's Day. It is 1 billion miles beyond Pluto.
On Tuesday, based on early, fuzzy images taken the day before, scientists said Ultima Thule resembled a bowling pin. But when better, closer pictures arrived, a new consensus emerged Wednesday.
“The bowling pin is gone. It's a snowman!” lead scientist Alan Stern informed the world from Johns Hopkins University's Applied Physics Laboratory, home to Mission Control in Laurel.
The bowling pin image is “so 2018,” joked Stern, who is with the Southwest Research Institute.
The celestial body was nicknamed Ultima Thule – meaning “beyond the known world” – before scientists could say for sure whether it was one object or two. With the arrival of the photos, they are now calling the bigger sphere Ultima and the smaller one Thule. Thule is estimated to be 9 miles across, while Ultima is thought to be 12 miles.
Scientist Jeff Moore of NASA's Ames Research Center said the two spheres formed when icy, pebble-size pieces coalesced in space billions of years ago. Then the spheres spiraled closer to each other until they gently touched – as slowly as parking a car here on Earth at just a mile or two per hour – and stuck together.
The two-lobed object is what is known as a “contact binary.” It is the first contact binary NASA has ever explored. Having formed 4.5 billion years ago, when the solar system was taking shape, it is also the most primitive object seen up close like this.
The snowman picture was taken a half-hour before the spacecraft's closest approach early Tuesday, from a distance of about 18,000 miles.
Stern noted that the team has received less than 1 percent of all the data stored aboard New Horizons. It will take nearly two years to get it all.