Oumuamua appeared to have been dropped in on our solar system from some great interstellar height, picking up even more speed on a slingshot-like loop around the sun before soaring away for parts unknown. It is now already halfway to Jupiter, too far for a rendezvous mission and rapidly fading from the view of Earth’s most powerful telescopes. Astronomers scrambling to glimpse the fading object have revealed additional oddities. ‘Oumuamua was never seen to sprout a comet-like tail after getting close to the sun, hinting it is not a relatively fresh bit of icy flotsam from the outskirts of a...