The faraway space snowman visited by Nasa last month has a surprisingly flat – not round – behind.
New photos from the New Horizons spacecraft offer a new perspective on the small cosmic body 4bn miles (6.4bn miles) away. The two-lobed object, nicknamed Ultima Thule, is actually flatter on the backside than originally thought, according to scientists.
Pictures released late last week – taken shortly after the closest approach to New Year's Day – provide an outline of the side not illuminated by the sun.
When viewed from the front, Ultima Thule still resembles a two-ball snowman. But from the side, the snowman looks squashed, sort of like a lemon and pie stuck together, end to end.
"Seeing more data has significantly changed our view," said Southwest Research Institute's Alan Stern, lead scientist, in a statement. "It would be closer to reality to say Ultima Thule's shape is flatter, like a pancake. But more importantly, the new images are creating scientific puzzles about how such an object could even be formed. We've never seen something like this orbiting the sun. "
Project scientist Hal Weaver of the Johns Hopkins University, home to the New Horizons flight control center, said the findings should spark new theories about how such primitive objects formed early in the solar system.
Ultima Thule – considered a contact binary – is the most distant world ever explored. New Horizons, which is the first to be visited by Pluto in 2015, is hoping to target an even more distant celestial object 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 miles) beyond Ultima Thule. It will take another one and a half years to get back all the flyby data.