At all.-Its lobes came together in a very gentle collision 'Different chemical changes that might happen don't occur,' said astronomer Will Grundy of the Lowell Observatory in Flagstaff, Ariz., leader of the project's surface composition team. Scientists think variations in daily and seasonal temperatures have probably only affected a very shallow surface layer of the Kuiper Belt object, ranging from a few millimeters to a few meters. Since it has never gotten warmer than about -350 degrees Fahrenheit, it has been well preserved since its formation shortly after the solar system was born.ĭuring its 293-year orbit around the sun, some regions of Ultima Thule receive no sunlight for decades at a time, while others face the sun for decades straight. Ultima Thule is about 43 times farther from the sun than we are, and as a result, it receives 900 times less sunlight than we do on Earth. It has been essentially undisturbed for more than 4 billion years Here are seven things we've learned about Ultima Thule so far:

The full download won't be complete until mid-2020. The new report is based on only 10% of all the data collected by New Horizons during its flyby. Only later did they fuse together, scientists believe. Ultima Thule is what's called a contact binary object, consisting of two lobes that formed separately through an accumulation of small particles of gas and dust. 'We had never seen something that was so primordial, so unchanged since the early formation days,' said Alan Stern, the principal investigator for the New Horizons mission. Its surface is barely heated by the sun, which is about 4 billion miles away, according to an initial analysis of New Horizons data published in Friday's edition of the journal Science. Ultima Thule has spent most of its 4.5 billion years frozen in time in the Kuiper Belt, a doughnut-shaped region beyond Neptune that contains remnants from the solar system's early days. The data it captured is now giving scientists a rare glimpse into the solar system's early days.

NASA's New Horizons spacecraft zipped past Ultima Thule on New Year's Eve (Pacific time), flying within 2,200 miles of the space rock's rust-colored surface.

The Farthest Place by E. Barnes