NASA’s New Horizons spacecraft beamed back the first close-up image of its target, Ultima Thule, revealing it’s a “contact binary”—two space rocks stuck together. KNAU’s Melissa Sevigny reports.
This is the most primitive contact binary ever explored by a spacecraft. It likely formed four and a half billion years ago by a process called “accretion.” Particles of rock and rubble melded into two round objects, which then slowly spiraled together until they stuck.
Will Grundy of Lowell Observatory says it’s a glimpse of how the solar system formed. "It’s a great example of something that was always theoretically imagined but we didn’t have an example of it, and so you’re never quite sure if your imagination is running wild or if that’s a real thing," he says. "But now I think people will start seeing contact binaries everywhere, because it’s clear the universe can make them."
Early results also show the object is red in color, which may mean it’s covered in exotic ices. More data will return from the spacecraft over the next year and a half.
