An ancient visit by an alien star
A wandering binary star sideswiped the solar system some 70,000 years ago, knocking dozens of far-flung comets and asteroids into unusual orbits. The glow of the red star’s fleeting flyby may have been witnessed by early human ancestors and Neanderthals, and scientists believe the gravitational effects of the prehistoric close encounter are still evident in the outer solar system today. The red dwarf and its smaller brown dwarf companion, jointly known as Scholz’s star, was first identified back in 2015. The star is currently 20 light-years from Earth, but researchers used its motion and velocity to trace its path backward through space. They calculate that it came within less than one light-year of the sun as it passed through the Oort cloud—a swarm of more than a trillion icy objects surrounding the outer edge of the solar system. Based on their unusual, V-shaped orbits, scientists suspect that at least 36 objects were nudged into new positions by the passing star’s gravity, TheWashingtonPost.com reports. The positions of these bodies “fits the close encounter with Scholz’s star,” says study author Carlos de la Fuente Marcos. His team also identified eight unusual comets that may have originated outside our solar system.
Michael Osadciw/University of Rochester, Jill Gregory/Mount Sinai Health System/licensed under CC-BY-ND, Newscom ■