Mexico wave — July 11, 1991 eclipse

During the total solar eclipse over Mexico City, dozens filmed a metallic object hovering in the sky. Spread by Jaime Maussan, it ignited Mexican ufology; one of the most documented sighting waves.

The wave (also Mexican wave outside North America) is a type of metachronal rhythm achieved in a packed stadium or other large seated venue, when successive groups of spectators briefly stand and raise their arms. Immediately upon stretching to full height, the spectator returns to the usual seated position. The result is a wave of standing spectators that travels through the crowd, even though individual spectators never move away from their seats. In many large arenas the crowd is seated in a contiguous circuit all the way around the sport field, and so the wave is able to travel continuously around the arena; in discontiguous seating arrangements, the wave can instead reflect back and forth through the crowd. When the gap in seating is narrow, the wave can sometimes pass through it. Usually only one wave crest will be present at any given time in an arena, although simultaneous, counter-rotating waves have been produced. The wave first appeared in U.S. sports events in the late 1970s to early 1980s. Televised instances at many matches of the 1986 FIFA World Cup in Mexico brought it to a global audience and led to the name "Mexican wave" in English-speaking countries outside North America.