Free Astronomy Magazine March-April 2019

23 MARCH-APRIL 2019 SPACE CHRONICLES cipal Investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado. “Never be- fore has any space- craft team tracked down such a small body at such high speed so far away in the abyss of space. New Horizons has set a new bar for state- of-the-art spacecraft navigation.” The new images — taken from as close as 17,000 miles (27,000 kilometers) on ap- proach — revealed Ultima Thule as a “contact binary,” con- sisting of two con- nected spheres. End to end, the world measures 19 miles (31 kilometers) in length. The team has dubbed the larger sphere “Ul- T he first color image of Ultima Thule, taken at a distance of 85,000 miles (137,000 kilometers) at 4:08 Universal Time on January 1, 2019, highlights its reddish surface. At left is an en- hanced color image taken by the Multispectral Visible Imaging Camera (MVIC), produced by com- bining the near infrared, red and blue channels. The center image taken by the Long-Range Reconnaissance Imager (LORRI) has a higher spatial resolution than MVIC by approximately a factor of five. At right, the color has been overlaid onto the LORRI image to show the color uni- formity of the Ultima and Thule lobes. Note the reduced red coloring at the neck of the object. [NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute] A n illustration of New Horizons’ flyby of 2014 MU69, also known as Ultima Thule, on New Year’s Day in 2019. [NASA/JHUAPL/SwRI/Alex Parker] tima” (12 miles/19 kilometers across) and the smaller sphere “Thule” (9 miles/14 kilometers across). The team says that the two spheres likely joined as early as 99 percent of the way back to the formation of the solar system, colliding no faster than two cars in a fender-bender. “New Horizons is like a time ma- chine, taking us back to the birth of the solar system. We are seeing a physical representation of the be- ginning of planetary formation, frozen in time,” said Jeff Moore, New Horizons Geology and Geo- physics team lead. “Studying Ultima Thule is helping us understand how planets form — both those in our own solar system and those orbit- ing other stars in our galaxy.” Data from the New Year’s Day flyby will continue to arrive over the next weeks and months, with much higher resolution images yet to come. “In the coming months, New Horizons will transmit dozens of data sets to Earth, and we’ll write new chapters in the story of Ultima Thule — and the solar system,” said Helene Winters, New Horizons Proj- ect Manager. !