What happened
In 1883 a young cowhand, Robert Reed Ellison, driving cattle through Paisano Pass, saw a flickering light in the distance and wondered whether it was an Apache campfire. Two years later settlers Joe and Sally Humphreys described their first sighting. Ever since, on clear nights on the plain between Marfa and Paisano Pass, facing the Chinati Mountains, people have seen lights that appear, merge, split, rise and fade. Stories have grown up around them: that they are the ghosts of Spanish conquistadors searching for gold; that during a blizzard the lights led Mrs. W. T. Giddings’s lost father to a cave where he sheltered from the storm; and during the First World War some feared they were enemy signals for an invasion. A viewing area was built on US 90, about nine miles east of Marfa, and in 2003 a viewing centre opened there, drawing tourists every night.
Witnesses
Robert Reed Ellison (1883) and Joe and Sally Humphreys (1885) in accounts written down later; since then thousands of residents and tourists.
Explanations and hypotheses
Many explanations have been offered: electrostatic discharge, swamp gas, moonlight reflecting off veins of mica. The Handbook of Texas considers the most plausible to be a mirage-like effect – light bent at the boundary between layers of cold and warm air, common in the high desert. Sceptics add that some sightings from the viewing area are the lights of distant cars and houses. The dates of the earliest accounts come from recollections written down years later, so they are hard to verify.
Disputed A likely explanation exists, but some of the facts are still disputed.
Sources
More: Wikipedia (en)