NASA JUST RELEASED the best images yet of Ultima Thule, the most distant world ever visited by a spacecraft. You’ll want to grab your 3D glasses if you’ve got ’em—we’re going stereoscopic.
On New Years’ Eve, following a 13-year trip to deep space, NASA’s New Horizons spacecraft made a close pass of Ultima Thule, a small, icy world drifting 4 billion miles from the sun in the unexplored “third zone” of our solar system. The probe zipped by at upwards of 31,000 miles per hour, about the same speed it was going when it passed Pluto in 2015. But Pluto is 100 times the size of Ultima, which measures just 20 miles long. So New Horizons had days to capture photographs and spectrographic readings of the former planet, but for this smaller cosmic quarry, it only had a matter of minutes. New Horizons’ visit was brief, but momentous: The mission’s success makes Ultima Thule by far the most distant object ever to be imaged up close.
New Horizons’ initial observations of Ultima Thule have been trickling back to Earth since the dawn of the new year. The transmission time between the edge of the solar system and our planet is a little more than six hours, and the download rate is just 500 bits per second, so the lowest-resolution imagery arrived first: New Years’ Day brought but a few tantalizing pixels, and Ultima Thule appeared as a bowling-pin-shaped blur. A day later, things improved dramatically: Color imagery confirmed Ultima Thule is red but dark, like potting soil, and the pin resolved into a snowman-shaped world with two distinct lobes. “What you’re seeing is the first ‘contact binary’ ever explored by spacecraft,” said New Horizons principal investigator Alan Stern. “Two completely separate objects joined together.” The New Horizons team named the larger orb “Ultima” and the smaller one “Thule.”