East of this west Texas town, lights have been watched since 1883: basketball-sized spheres that hang over the desert, split, merge and go out. The cowboy Robert Ellison recorded the first, taking them for Apache campfires. University physicists showed in 2004 that a good share of them are headlights on Highway 67 refracted through layers of warm air. A share — but not all, and it cannot account for the sightings that predate cars.