ON THE NIGHT of July 1st, in a remote corner of Chile, a small robotic telescope noticed something in the sky. What at first seemed a routine detection of an object travelling through the solar system soon turned out to be anything but. The object’s trajectory revealed it to be a much rarer visitor than first thought. Formed around a distant star elsewhere in the Milky Way, it is an interstellar wanderer, not a merely interplanetary one.