Update November 2019: 2014 MU69 has been officially named Arrokoth.
A sequence showing the propeller-like rotation of Kuiper Belt Object 2014 MU69.
This movie shows the propeller-like rotation of Ultima Thule in the seven hours between 20:00 UT (3 p.m. ET) on Dec. 31, 2018, and 05:01 UT (12:01 a.m.) on Jan. 1, 2019, as seen by the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons as the spacecraft sped toward its close encounter with the Kuiper Belt object at 05:33 UT (12:33 a.m. ET) on Jan. 1.
During this deep-space photo shoot – part of the farthest planetary flyby in history – New Horizons' range to Ultima Thule decreased from 310,000 miles (500,000 kilometers, farther than the distance from the Earth to the Moon) to just 17,100 miles (28,000 kilometers), during which the images became steadily larger and more detailed.
The team processed two different image sequences.
The bottom sequence shows the images at their original relative sizes, while the top corrects for the changing distance, so that Ultima Thule (officially named 2014 MU69) appears at constant size but becomes more detailed as the approach progresses.
All the images have been sharpened using scientific techniques that enhance detail. The original image scale is 1.5 miles (2.5 kilometers) per pixel in the first frame, and 0.08 miles (0.14 kilometers) per pixel in the last frame. The rotation period of Ultima Thule is about 16 hours, so the movie covers a little under half a rotation. Among other things, the New Horizons science team will use these images to help determine the three-dimensional shape of Ultima Thule, in order to better understand its nature and origin.
The raw images included in the movie are available on the New Horizons LORRI website. New Horizons downlinked the two highest-resolution images in this movie immediately after the Jan. 1 flyby, but the more distant images were sent home on Jan. 12-14, after a week when New Horizons was too close to the Sun (from Earth's point of view) for reliable communications. New Horizons will continue to transmit images – including its closest views of Ultima Thule – and data for the next many months.