Left: what the tunnel would look like; right: what the sky does look like. (Image Credit Below) Mysterious structures in the sky that have puzzled astronomers for decades might finally have an explanation – and it's quite something. The North Polar Spur and the Fan Region, on opposite sides of the sky, may be connected by a vast system of magnetized filaments. These form a structure resembling a tunnel that circles the Solar System, and many nearby stars besides. "If we were to look up in the sky," said astronomer Jennifer West of the University of Toronto in Canada, "we...