On its first asteroid flyby on Nov. 1, NASA’s Lucy mission found that the primary belt asteroid Dinkinesh has a small moon orbiting it. Now, extra photographs have revealed one other shock: Dinkinesh’s moon is just not one, however two small satellites. The dual moons initially appeared as one as a result of they’re so shut collectively, they contact as they orbit.
Dinkinesh — affectionately often known as “Dinky” — is about 2,500 ft (790 meters) in diameter, making it the smallest primary belt asteroid ever explored by a spacecraft. Astronomers have been observing Dinkinesh since 1999, and so they knew that the asteroid was considerably uncommon by the best way its brightness fluctuated. However they didn’t predict that the diminutive asteroid was harboring a moon — not to mention two. Primarily based on Lucy’s photographs, its moons look like a mixed 720 ft (220 m) round.
When a pair of celestial objects orbit this shut collectively, scientists name it a “contact binary.” These binaries collectively tackle a peanut or pear form, and so they might not be uncommon within the photo voltaic system. For instance, the New Horizons spacecraft confirmed that Arrokoth, an icy object within the Kuiper Belt past the orbit of Neptune, was a contact binary in 2019. A handful of different asteroids and comets appear to be contact binaries as nicely.
What makes Dinkinesh’s moons uncommon is that each lobes are roughly the identical measurement; The overwhelming majority of contact binaries are lopsided. It’s kind of of a thriller as to how two equally-sized our bodies would stick collectively gravitationally, based on NASA researchers.
“It’s puzzling, to say the least,” Hal Levison, an astronomer on the Southwest Analysis Institute and one among Lucy’s principal investigators, mentioned in a assertion. “That is going to be enjoyable for the scientific neighborhood to determine.”
Dinkinesh is not even Lucy’s major purpose — the asteroid flyby was added to the probe’s schedule as a warm-up for its primary mission, surveying Jupiter’s Trojan asteroids for the primary time. If all goes nicely, Lucy will attain these distant house rocks in 2027. However this preliminary take a look at signifies that Lucy’s tools is working even higher than astronomers anticipated. The analysis crew now plans to have Lucy snap photographs of one other primary belt asteroid, Donaldjohanson, because it zooms previous in 2025.
