The remote room key, which was visited by NASA last month, has a surprisingly flat – not round – behind.
New images from New Horizon's spacecraft provide a new perspective on the small cosmic body 4 miles away. The two-lobed object, called Ultima Thule, is actually flatter at the back than originally thought, according to researchers.
Pictures released last week – taken shortly after closest approach on New Year's Day – give an overview of the page that is not illuminated by the sun.
When looking at the front, Ultima Thule still looks like a two-cold snowman. But from the side, the snowman looks like a lemon and a pie stuck together and ends.
"Seeing more data has significantly changed our point of view," research scientist Alan Stern, a leading researcher, said in a statement. "It would be closer to reality to say that Ultima Thule's shape is flatter as a pancake. But more importantly, the new images create scientific jigsaw puzzles of how such an object could even be formed. We have never seen anything like this circling the sun . "
Project researcher Hal Weaver from Johns Hopkins University, home to the New Horizon air traffic control center, said the finding should spark new theories on how such primitive objects were formed early in the solar system.
Ultima Thule – considered a contact binary – is the farthest world ever explored. New horizons glide past it at high speed after being the first visitor to Pluto in 2015. Mission consultants hope to target an even farther celestial body in this so-called Kuiper Belt on the frozen fringes of the solar system if the spacecraft remains healthy.
New Horizons is already 32m miles (52m) off Ultima Thule. It takes another six months to slow down all the flyby data.