A mysterious symphony of rapid-fire lightning bolts used to create the greatest light show on Earth over the Catatumbo River in Venezuela -- until suddenly they stopped and no one knew why.
More than 40,000 bolts ripped across the night sky as many as 300 nights a year for nine hours at a time. It occurred so frequently that the phenomenon became known as "Relampago de Catatumbo," or "Catatumbo Lightning."
For centuries, the indigenous people of Northwestern Venezuela called the phenomenon "rib a-ba" or "river of fire in the sky." Ancient mariners supposedly used the lightning for navigation.
"I saw my first lightning when I was 8 years old," said Erik Quiroga, a native of the area. "I thought it was a smile from the night sky."
Quiroga grew up in the foothills of the Andes Mountains and said local farmers and villagers would marvel at the lightning and its recurrence every night.
"They have no idea that this lightning flashing around all night is something unique," said Alan Highton, a tour operator based on Lake Maracaibo who lives part-time with the indigenous people. "It doesn't occur anywhere else in the world."
Out on the lake, tin and plywood shacks built on stilts rose out of the water. It was 100 degrees and incredibly humid. There were no cars or bicycles, just boats. Highton said that for generations, the villagers didn't pay much attention to the lightning until visitors started coming and spending all night on the water to watch the light show.
Then suddenly, last year, the lightning disappeared, and they took notice.
"We did realize the lightning stopped," Highton said. "To us, it was a mysterious thing and we do not have the information to say exactly why."
For a several months starting January 2010, not one lightning bolt was seen, sparking concern it was gone forever. Then, as mysteriously as it had stopped, it began again, as proven from NASA satellite data.
There are lots of theories on why the lightning stopped and then started again.
Quiroga suspected that the change could have been a result of a shift from El Nino to La Nina, global weather patterns that are characterized by unusually warm and cold ocean temperatures, respectfully, in the eastern equatorial Pacific Ocean.
The change might also be tied to bizarre weather elsewhere in the world: deadly and frequent tornadoes, floods and droughts.
Now, some scientists believe the celestial wonder was disrupted because El Nino caused a severe drought across Venezuela, where rain disappeared and river beds ran dry.
Perhaps the mystery of why the lightning disappeared might have something to do with whatever reason the phenomenon happened in the first place.
Quiroga offered his own theory.
"Black water absorbs more energy," he said. "The winds that come down from the mountains [are] pushing that energy up into the air, and that's the root of the formation of the lighting."
Highton offered a different idea for what might be happening.
"My own opinion is there is a very intense low pressure in this entire basin," he said. "As night falls and this causes these towering clouds in several different places, you can get six or seven lightning storms around you at the same time."