Ten years ago. That's when they arrived. Comets painted white streaks across the sky - more than humanity had ever seen at once. The evening sky surged with unnatural colour, a thousand sunsets at once. And then, they were here. Well - in a way. Leaders sent their armies in and they passed through the visitors like mist. Scientists brought machines that bleeped and flashed but recorded nothing. They did no harm, so we left them alone. They became as normal as clouds. For ten years these giant ghosts, these vast phantasms, have walked the Earth. We do not know their purpose. But they look lost.